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Sylvia Else
Guest
On 20-Apr-20 3:41 am, Cursitor Doom wrote:
Not sure \"too hot to touch\" is a good measure, because a good conductor
of heat will feel too hot even at a modest temperature.
If a single bigger heat sink is not an option, you could use a 7809 or
7810 to drive the 7805, splitting the heat output roughly between them.
Sylvia.
Gentlemen,
in pursuance of what is turning out to be a jinxed project (installing a
dashcam) I\'m attempting to drop 14.5V (the normal battery voltage whilst
the engine is running) to 5V for the camera. The camera draws at most
300mA so the regulator (an L7805CV) shouldn\'t find that task too much of
a struggle, since it only has to disspate just under 3 Watts by my
reckoning. I\'d have thought this reasonably large heatsink (see 20p piece
for scale comparison) would be overkill. Unfortunately it isn\'t, though.
Even with a low ambient temp of about 65\'F it gets a bit too hot to touch
after a few minutes, so once in the car in a couple of months with a
T_amb north of 100\'F, it hasn\'t a hope in hell of preventing the reg from
going up in smoke.
Apart from advising me to permanantly give up electronics, has anyone got
any constructive suggestions to make here?
TIA.
Not sure \"too hot to touch\" is a good measure, because a good conductor
of heat will feel too hot even at a modest temperature.
If a single bigger heat sink is not an option, you could use a 7809 or
7810 to drive the 7805, splitting the heat output roughly between them.
Sylvia.
S
server
Guest
On Wed, 5 Jan 2022 14:07:30 +1100, Sylvia Else <sylvia@email.invalid>
wrote:
There are cute little 3-pin potted switching regulators that drop into
a 7805 footprint.
--
I yam what I yam - Popeye
wrote:
On 20-Apr-20 3:41 am, Cursitor Doom wrote:
Gentlemen,
in pursuance of what is turning out to be a jinxed project (installing a
dashcam) I\'m attempting to drop 14.5V (the normal battery voltage whilst
the engine is running) to 5V for the camera. The camera draws at most
300mA so the regulator (an L7805CV) shouldn\'t find that task too much of
a struggle, since it only has to disspate just under 3 Watts by my
reckoning. I\'d have thought this reasonably large heatsink (see 20p piece
for scale comparison) would be overkill. Unfortunately it isn\'t, though.
Even with a low ambient temp of about 65\'F it gets a bit too hot to touch
after a few minutes, so once in the car in a couple of months with a
T_amb north of 100\'F, it hasn\'t a hope in hell of preventing the reg from
going up in smoke.
Apart from advising me to permanantly give up electronics, has anyone got
any constructive suggestions to make here?
TIA.
Not sure \"too hot to touch\" is a good measure, because a good conductor
of heat will feel too hot even at a modest temperature.
If a single bigger heat sink is not an option, you could use a 7809 or
7810 to drive the 7805, splitting the heat output roughly between them.
Sylvia.
There are cute little 3-pin potted switching regulators that drop into
a 7805 footprint.
--
I yam what I yam - Popeye
S
Sylvia Else
Guest
On 05-Jan-22 4:16 pm, jlarkin@highlandsniptechnology.com wrote:
I hadn\'t come across those. Cursitor might be interested in
https://www.digikey.com/en/products/detail/mornsun-america-llc/K7805M-1000R3/13168132
Sylvia.
On Wed, 5 Jan 2022 14:07:30 +1100, Sylvia Else <sylvia@email.invalid
wrote:
On 20-Apr-20 3:41 am, Cursitor Doom wrote:
Gentlemen,
in pursuance of what is turning out to be a jinxed project (installing a
dashcam) I\'m attempting to drop 14.5V (the normal battery voltage whilst
the engine is running) to 5V for the camera. The camera draws at most
300mA so the regulator (an L7805CV) shouldn\'t find that task too much of
a struggle, since it only has to disspate just under 3 Watts by my
reckoning. I\'d have thought this reasonably large heatsink (see 20p piece
for scale comparison) would be overkill. Unfortunately it isn\'t, though.
Even with a low ambient temp of about 65\'F it gets a bit too hot to touch
after a few minutes, so once in the car in a couple of months with a
T_amb north of 100\'F, it hasn\'t a hope in hell of preventing the reg from
going up in smoke.
Apart from advising me to permanantly give up electronics, has anyone got
any constructive suggestions to make here?
TIA.
Not sure \"too hot to touch\" is a good measure, because a good conductor
of heat will feel too hot even at a modest temperature.
If a single bigger heat sink is not an option, you could use a 7809 or
7810 to drive the 7805, splitting the heat output roughly between them.
Sylvia.
There are cute little 3-pin potted switching regulators that drop into
a 7805 footprint.
I hadn\'t come across those. Cursitor might be interested in
https://www.digikey.com/en/products/detail/mornsun-america-llc/K7805M-1000R3/13168132
Sylvia.
S
server
Guest
On Wed, 5 Jan 2022 16:25:22 +1100, Sylvia Else <sylvia@email.invalid>
wrote:
Check this one out:
https://www.digikey.com/en/products/detail/xp-power/SRH05S12/8021461?s=N4IgTCBcDaIMoCUASAGArHAjBAugXyA
72 volts max input! I use it to drop 48 volts down to a more managable
12.
--
I yam what I yam - Popeye
wrote:
On 05-Jan-22 4:16 pm, jlarkin@highlandsniptechnology.com wrote:
On Wed, 5 Jan 2022 14:07:30 +1100, Sylvia Else <sylvia@email.invalid
wrote:
On 20-Apr-20 3:41 am, Cursitor Doom wrote:
Gentlemen,
in pursuance of what is turning out to be a jinxed project (installing a
dashcam) I\'m attempting to drop 14.5V (the normal battery voltage whilst
the engine is running) to 5V for the camera. The camera draws at most
300mA so the regulator (an L7805CV) shouldn\'t find that task too much of
a struggle, since it only has to disspate just under 3 Watts by my
reckoning. I\'d have thought this reasonably large heatsink (see 20p piece
for scale comparison) would be overkill. Unfortunately it isn\'t, though.
Even with a low ambient temp of about 65\'F it gets a bit too hot to touch
after a few minutes, so once in the car in a couple of months with a
T_amb north of 100\'F, it hasn\'t a hope in hell of preventing the reg from
going up in smoke.
Apart from advising me to permanantly give up electronics, has anyone got
any constructive suggestions to make here?
TIA.
Not sure \"too hot to touch\" is a good measure, because a good conductor
of heat will feel too hot even at a modest temperature.
If a single bigger heat sink is not an option, you could use a 7809 or
7810 to drive the 7805, splitting the heat output roughly between them.
Sylvia.
There are cute little 3-pin potted switching regulators that drop into
a 7805 footprint.
I hadn\'t come across those. Cursitor might be interested in
https://www.digikey.com/en/products/detail/mornsun-america-llc/K7805M-1000R3/13168132
Sylvia.
Check this one out:
https://www.digikey.com/en/products/detail/xp-power/SRH05S12/8021461?s=N4IgTCBcDaIMoCUASAGArHAjBAugXyA
72 volts max input! I use it to drop 48 volts down to a more managable
12.
--
I yam what I yam - Popeye
C
Cursitor Doom
Guest
On Wed, 5 Jan 2022 16:25:22 +1100, Sylvia Else <sylvia@email.invalid>
wrote:
Have you been asleep, Sylvia? That post was nearly two years ago! That
issue got solved long ago but thanks for trying anyway.
wrote:
On 05-Jan-22 4:16 pm, jlarkin@highlandsniptechnology.com wrote:
On Wed, 5 Jan 2022 14:07:30 +1100, Sylvia Else <sylvia@email.invalid
wrote:
On 20-Apr-20 3:41 am, Cursitor Doom wrote:
Gentlemen,
in pursuance of what is turning out to be a jinxed project (installing a
dashcam) I\'m attempting to drop 14.5V (the normal battery voltage whilst
the engine is running) to 5V for the camera. The camera draws at most
300mA so the regulator (an L7805CV) shouldn\'t find that task too much of
a struggle, since it only has to disspate just under 3 Watts by my
reckoning. I\'d have thought this reasonably large heatsink (see 20p piece
for scale comparison) would be overkill. Unfortunately it isn\'t, though.
Even with a low ambient temp of about 65\'F it gets a bit too hot to touch
after a few minutes, so once in the car in a couple of months with a
T_amb north of 100\'F, it hasn\'t a hope in hell of preventing the reg from
going up in smoke.
Apart from advising me to permanantly give up electronics, has anyone got
any constructive suggestions to make here?
TIA.
Not sure \"too hot to touch\" is a good measure, because a good conductor
of heat will feel too hot even at a modest temperature.
If a single bigger heat sink is not an option, you could use a 7809 or
7810 to drive the 7805, splitting the heat output roughly between them.
Sylvia.
There are cute little 3-pin potted switching regulators that drop into
a 7805 footprint.
I hadn\'t come across those. Cursitor might be interested in
https://www.digikey.com/en/products/detail/mornsun-america-llc/K7805M-1000R3/13168132
Sylvia.
Have you been asleep, Sylvia? That post was nearly two years ago! That
issue got solved long ago but thanks for trying anyway.
S
server
Guest
On Wed, 05 Jan 2022 16:41:18 +0000, Cursitor Doom <cd@notformail.com>
wrote:
Were you born rude, Doomie?
--
I yam what I yam - Popeye
wrote:
On Wed, 5 Jan 2022 16:25:22 +1100, Sylvia Else <sylvia@email.invalid
wrote:
On 05-Jan-22 4:16 pm, jlarkin@highlandsniptechnology.com wrote:
On Wed, 5 Jan 2022 14:07:30 +1100, Sylvia Else <sylvia@email.invalid
wrote:
On 20-Apr-20 3:41 am, Cursitor Doom wrote:
Gentlemen,
in pursuance of what is turning out to be a jinxed project (installing a
dashcam) I\'m attempting to drop 14.5V (the normal battery voltage whilst
the engine is running) to 5V for the camera. The camera draws at most
300mA so the regulator (an L7805CV) shouldn\'t find that task too much of
a struggle, since it only has to disspate just under 3 Watts by my
reckoning. I\'d have thought this reasonably large heatsink (see 20p piece
for scale comparison) would be overkill. Unfortunately it isn\'t, though.
Even with a low ambient temp of about 65\'F it gets a bit too hot to touch
after a few minutes, so once in the car in a couple of months with a
T_amb north of 100\'F, it hasn\'t a hope in hell of preventing the reg from
going up in smoke.
Apart from advising me to permanantly give up electronics, has anyone got
any constructive suggestions to make here?
TIA.
Not sure \"too hot to touch\" is a good measure, because a good conductor
of heat will feel too hot even at a modest temperature.
If a single bigger heat sink is not an option, you could use a 7809 or
7810 to drive the 7805, splitting the heat output roughly between them.
Sylvia.
There are cute little 3-pin potted switching regulators that drop into
a 7805 footprint.
I hadn\'t come across those. Cursitor might be interested in
https://www.digikey.com/en/products/detail/mornsun-america-llc/K7805M-1000R3/13168132
Sylvia.
Have you been asleep, Sylvia? That post was nearly two years ago!
Were you born rude, Doomie?
--
I yam what I yam - Popeye
A
amdx
Guest
On 4/19/2020 12:41 PM, Cursitor Doom wrote:
A series 20Ω 5 watt resistor between the 14.5V and the 5 V regulator
would move a lot of that heat.
                                           Mikek
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus
Gentlemen,
in pursuance of what is turning out to be a jinxed project (installing a
dashcam) I\'m attempting to drop 14.5V (the normal battery voltage whilst
the engine is running) to 5V for the camera. The camera draws at most
300mA so the regulator (an L7805CV) shouldn\'t find that task too much of
a struggle, since it only has to disspate just under 3 Watts by my
reckoning. I\'d have thought this reasonably large heatsink (see 20p piece
for scale comparison) would be overkill. Unfortunately it isn\'t, though.
Even with a low ambient temp of about 65\'F it gets a bit too hot to touch
after a few minutes, so once in the car in a couple of months with a
T_amb north of 100\'F, it hasn\'t a hope in hell of preventing the reg from
going up in smoke.
Apart from advising me to permanantly give up electronics, has anyone got
any constructive suggestions to make here?
TIA.
A series 20Ω 5 watt resistor between the 14.5V and the 5 V regulator
would move a lot of that heat.
                                           Mikek
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus
A
amdx
Guest
On 1/5/2022 10:57 AM, amdx wrote:
                             Mikek
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus
On 4/19/2020 12:41 PM, Cursitor Doom wrote:
Gentlemen,
in pursuance of what is turning out to be a jinxed project (installing a
dashcam) I\'m attempting to drop 14.5V (the normal battery voltage whilst
the engine is running) to 5V for the camera. The camera draws at most
300mA so the regulator (an L7805CV) shouldn\'t find that task too much of
a struggle, since it only has to disspate just under 3 Watts by my
reckoning. I\'d have thought this reasonably large heatsink (see 20p
piece
for scale comparison) would be overkill. Unfortunately it isn\'t, though.
Even with a low ambient temp of about 65\'F it gets a bit too hot to
touch
after a few minutes, so once in the car in a couple of months with a
T_amb north of 100\'F, it hasn\'t a hope in hell of preventing the reg
from
going up in smoke.
Apart from advising me to permanantly give up electronics, has anyone
got
any constructive suggestions to make here?
TIA.
A series 20Ω 5 watt resistor between the 14.5V and the 5 V regulator
would move a lot of that heat.
                                           Mikek
Oh, I see Ricky C beat me to it.
                             Mikek
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus
C
Cursitor Doom
Guest
On Wed, 05 Jan 2022 08:53:21 -0800, jlarkin@highlandsniptechnology.com
wrote:
I *was* being polite! I thanked Sylvie but you snipped that bit off!
wrote:
On Wed, 05 Jan 2022 16:41:18 +0000, Cursitor Doom <cd@notformail.com
wrote:
On Wed, 5 Jan 2022 16:25:22 +1100, Sylvia Else <sylvia@email.invalid
wrote:
On 05-Jan-22 4:16 pm, jlarkin@highlandsniptechnology.com wrote:
On Wed, 5 Jan 2022 14:07:30 +1100, Sylvia Else <sylvia@email.invalid
wrote:
On 20-Apr-20 3:41 am, Cursitor Doom wrote:
Gentlemen,
in pursuance of what is turning out to be a jinxed project (installing a
dashcam) I\'m attempting to drop 14.5V (the normal battery voltage whilst
the engine is running) to 5V for the camera. The camera draws at most
300mA so the regulator (an L7805CV) shouldn\'t find that task too much of
a struggle, since it only has to disspate just under 3 Watts by my
reckoning. I\'d have thought this reasonably large heatsink (see 20p piece
for scale comparison) would be overkill. Unfortunately it isn\'t, though.
Even with a low ambient temp of about 65\'F it gets a bit too hot to touch
after a few minutes, so once in the car in a couple of months with a
T_amb north of 100\'F, it hasn\'t a hope in hell of preventing the reg from
going up in smoke.
Apart from advising me to permanantly give up electronics, has anyone got
any constructive suggestions to make here?
TIA.
Not sure \"too hot to touch\" is a good measure, because a good conductor
of heat will feel too hot even at a modest temperature.
If a single bigger heat sink is not an option, you could use a 7809 or
7810 to drive the 7805, splitting the heat output roughly between them.
Sylvia.
There are cute little 3-pin potted switching regulators that drop into
a 7805 footprint.
I hadn\'t come across those. Cursitor might be interested in
https://www.digikey.com/en/products/detail/mornsun-america-llc/K7805M-1000R3/13168132
Sylvia.
Have you been asleep, Sylvia? That post was nearly two years ago!
Were you born rude, Doomie?
I *was* being polite! I thanked Sylvie but you snipped that bit off!
S
Sylvia Else
Guest
On 06-Jan-22 3:41 am, Cursitor Doom wrote:
I came up as an unread post - probably as a result of my inadvertently
reversing the sort order on dates.
Still, I learned about the potted regulators, so it wasn\'t a complete
waste of time for me.
Sylvia.
On Wed, 5 Jan 2022 16:25:22 +1100, Sylvia Else <sylvia@email.invalid
wrote:
On 05-Jan-22 4:16 pm, jlarkin@highlandsniptechnology.com wrote:
On Wed, 5 Jan 2022 14:07:30 +1100, Sylvia Else <sylvia@email.invalid
wrote:
On 20-Apr-20 3:41 am, Cursitor Doom wrote:
Gentlemen,
in pursuance of what is turning out to be a jinxed project (installing a
dashcam) I\'m attempting to drop 14.5V (the normal battery voltage whilst
the engine is running) to 5V for the camera. The camera draws at most
300mA so the regulator (an L7805CV) shouldn\'t find that task too much of
a struggle, since it only has to disspate just under 3 Watts by my
reckoning. I\'d have thought this reasonably large heatsink (see 20p piece
for scale comparison) would be overkill. Unfortunately it isn\'t, though.
Even with a low ambient temp of about 65\'F it gets a bit too hot to touch
after a few minutes, so once in the car in a couple of months with a
T_amb north of 100\'F, it hasn\'t a hope in hell of preventing the reg from
going up in smoke.
Apart from advising me to permanantly give up electronics, has anyone got
any constructive suggestions to make here?
TIA.
Not sure \"too hot to touch\" is a good measure, because a good conductor
of heat will feel too hot even at a modest temperature.
If a single bigger heat sink is not an option, you could use a 7809 or
7810 to drive the 7805, splitting the heat output roughly between them.
Sylvia.
There are cute little 3-pin potted switching regulators that drop into
a 7805 footprint.
I hadn\'t come across those. Cursitor might be interested in
https://www.digikey.com/en/products/detail/mornsun-america-llc/K7805M-1000R3/13168132
Sylvia.
Have you been asleep, Sylvia? That post was nearly two years ago! That
issue got solved long ago but thanks for trying anyway.
I came up as an unread post - probably as a result of my inadvertently
reversing the sort order on dates.
Still, I learned about the potted regulators, so it wasn\'t a complete
waste of time for me.
Sylvia.
R
Rick C
Guest
On Wednesday, January 5, 2022 at 11:59:36 AM UTC-5, amdx wrote:
That was almost two years ago!!!
--
Rick C.
+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209
On 1/5/2022 10:57 AM, amdx wrote:
On 4/19/2020 12:41 PM, Cursitor Doom wrote:
Gentlemen,
in pursuance of what is turning out to be a jinxed project (installing a
dashcam) I\'m attempting to drop 14.5V (the normal battery voltage whilst
the engine is running) to 5V for the camera. The camera draws at most
300mA so the regulator (an L7805CV) shouldn\'t find that task too much of
a struggle, since it only has to disspate just under 3 Watts by my
reckoning. I\'d have thought this reasonably large heatsink (see 20p
piece
for scale comparison) would be overkill. Unfortunately it isn\'t, though.
Even with a low ambient temp of about 65\'F it gets a bit too hot to
touch
after a few minutes, so once in the car in a couple of months with a
T_amb north of 100\'F, it hasn\'t a hope in hell of preventing the reg
from
going up in smoke.
Apart from advising me to permanantly give up electronics, has anyone
got
any constructive suggestions to make here?
TIA.
A series 20Ω 5 watt resistor between the 14.5V and the 5 V regulator
would move a lot of that heat.
Mikek
Oh, I see Ricky C beat me to it.
That was almost two years ago!!!
--
Rick C.
+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209
T
Tabby
Guest
On Monday, 20 April 2020 at 00:43:51 UTC+1, gnuarm.del...@gmail.com wrote:
R on the input is easy & works. But 6v is too low.
Re automotive transients, cars today typically switch accessory sockets off when harsh transients are likely, so diode protection should suffice, or even none if you\'re willing to accept the risk.
On Sunday, April 19, 2020 at 1:41:52 PM UTC-4, Cursitor Doom wrote:
Gentlemen,
in pursuance of what is turning out to be a jinxed project (installing a
dashcam) I\'m attempting to drop 14.5V (the normal battery voltage whilst
the engine is running) to 5V for the camera. The camera draws at most
300mA so the regulator (an L7805CV) shouldn\'t find that task too much of
a struggle, since it only has to disspate just under 3 Watts by my
reckoning. I\'d have thought this reasonably large heatsink (see 20p piece
for scale comparison) would be overkill. Unfortunately it isn\'t, though..
Even with a low ambient temp of about 65\'F it gets a bit too hot to touch
after a few minutes, so once in the car in a couple of months with a
T_amb north of 100\'F, it hasn\'t a hope in hell of preventing the reg from
going up in smoke.
Apart from advising me to permanantly give up electronics, has anyone got
any constructive suggestions to make here?
TIA.
Remember that a 7 watt night light glows from the heat! If I get what you are saying you are using a heat sink about an inch square. That\'s not likely to be big enough.
But keep in mind these things are spec\'d to 85°C which is nearly hot enough to boil water. The fact that you can\'t touch it doesn\'t mean so much. Your finger doesn\'t like 50 °C. The device will survive much hotter temps than 85 °C.
Get a larger heat sink. Any piece of metal will do. I was going to make my own car charger and thought about using the metal of the ash tray for the heat sink.
You can also use a dropping resistor. Try a 20 ohm power resistor dropping 6 volts at 300 mA cutting the 3 watts to more like 1.2 watts. The resistor can get a lot hotter than the regulator with no ill effect. Don\'t keep them close though.
Here\'s a couple of 8 ohm parts.
https://www.ebay.com/itm/Lot-of-2-8-Ohm-5-Watt-Wirewound-Ceramic-Power-Resistors-5W/264557630772?hash=item3d98dd1534:g:TaAAAOSwyVdd6XTG
R on the input is easy & works. But 6v is too low.
Re automotive transients, cars today typically switch accessory sockets off when harsh transients are likely, so diode protection should suffice, or even none if you\'re willing to accept the risk.
T
Tabby
Guest
On Wednesday, 5 January 2022 at 03:07:38 UTC, Sylvia Else wrote:
But power will fail when the battery gets lowish.
On 20-Apr-20 3:41 am, Cursitor Doom wrote:
Gentlemen,
in pursuance of what is turning out to be a jinxed project (installing a
dashcam) I\'m attempting to drop 14.5V (the normal battery voltage whilst
the engine is running) to 5V for the camera. The camera draws at most
300mA so the regulator (an L7805CV) shouldn\'t find that task too much of
a struggle, since it only has to disspate just under 3 Watts by my
reckoning. I\'d have thought this reasonably large heatsink (see 20p piece
for scale comparison) would be overkill. Unfortunately it isn\'t, though.
Even with a low ambient temp of about 65\'F it gets a bit too hot to touch
after a few minutes, so once in the car in a couple of months with a
T_amb north of 100\'F, it hasn\'t a hope in hell of preventing the reg from
going up in smoke.
Apart from advising me to permanantly give up electronics, has anyone got
any constructive suggestions to make here?
TIA.
Not sure \"too hot to touch\" is a good measure, because a good conductor
of heat will feel too hot even at a modest temperature.
If a single bigger heat sink is not an option, you could use a 7809 or
7810 to drive the 7805, splitting the heat output roughly between them.
Sylvia.
But power will fail when the battery gets lowish.
R
Rick C
Guest
On Thursday, January 6, 2022 at 6:43:46 PM UTC-5, Tabby wrote:
Use a high voltage regulator that saturates and provides a virtual short when the battery voltage is too low. Then the output regulator still gets enough voltage to remain in operation.
--
Rick C.
-- Get 1,000 miles of free Supercharging
-- Tesla referral code - https://ts.la/richard11209
On Wednesday, 5 January 2022 at 03:07:38 UTC, Sylvia Else wrote:
On 20-Apr-20 3:41 am, Cursitor Doom wrote:
Gentlemen,
in pursuance of what is turning out to be a jinxed project (installing a
dashcam) I\'m attempting to drop 14.5V (the normal battery voltage whilst
the engine is running) to 5V for the camera. The camera draws at most
300mA so the regulator (an L7805CV) shouldn\'t find that task too much of
a struggle, since it only has to disspate just under 3 Watts by my
reckoning. I\'d have thought this reasonably large heatsink (see 20p piece
for scale comparison) would be overkill. Unfortunately it isn\'t, though.
Even with a low ambient temp of about 65\'F it gets a bit too hot to touch
after a few minutes, so once in the car in a couple of months with a
T_amb north of 100\'F, it hasn\'t a hope in hell of preventing the reg from
going up in smoke.
Apart from advising me to permanantly give up electronics, has anyone got
any constructive suggestions to make here?
TIA.
Not sure \"too hot to touch\" is a good measure, because a good conductor
of heat will feel too hot even at a modest temperature.
If a single bigger heat sink is not an option, you could use a 7809 or
7810 to drive the 7805, splitting the heat output roughly between them.
Sylvia.
But power will fail when the battery gets lowish.
Use a high voltage regulator that saturates and provides a virtual short when the battery voltage is too low. Then the output regulator still gets enough voltage to remain in operation.
--
Rick C.
-- Get 1,000 miles of free Supercharging
-- Tesla referral code - https://ts.la/richard11209
A
amdx
Guest
On 1/5/2022 9:43 PM, Rick C wrote:
                 Mikek
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus
On Wednesday, January 5, 2022 at 11:59:36 AM UTC-5, amdx wrote:
On 1/5/2022 10:57 AM, amdx wrote:
On 4/19/2020 12:41 PM, Cursitor Doom wrote:
Gentlemen,
in pursuance of what is turning out to be a jinxed project (installing a
dashcam) I\'m attempting to drop 14.5V (the normal battery voltage whilst
the engine is running) to 5V for the camera. The camera draws at most
300mA so the regulator (an L7805CV) shouldn\'t find that task too much of
a struggle, since it only has to disspate just under 3 Watts by my
reckoning. I\'d have thought this reasonably large heatsink (see 20p
piece
for scale comparison) would be overkill. Unfortunately it isn\'t, though.
Even with a low ambient temp of about 65\'F it gets a bit too hot to
touch
after a few minutes, so once in the car in a couple of months with a
T_amb north of 100\'F, it hasn\'t a hope in hell of preventing the reg
from
going up in smoke.
Apart from advising me to permanantly give up electronics, has anyone
got
any constructive suggestions to make here?
TIA.
A series 20Ω 5 watt resistor between the 14.5V and the 5 V regulator
would move a lot of that heat.
Mikek
Oh, I see Ricky C beat me to it.
That was almost two years ago!!!
OK, it doesn\'t count then!
                 Mikek
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This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus
L
LM
Guest
On Tue, 04 Jan 2022 21:41:32 -0800, jlarkin@highlandsniptechnology.com
wrote:
Those 70V regulators help a lot in that.
wrote:
I once wondered how can I get an input with widest voltage range.On Wed, 5 Jan 2022 16:25:22 +1100, Sylvia Else <sylvia@email.invalid
wrote:
On 05-Jan-22 4:16 pm, jlarkin@highlandsniptechnology.com wrote:
On Wed, 5 Jan 2022 14:07:30 +1100, Sylvia Else <sylvia@email.invalid
wrote:
On 20-Apr-20 3:41 am, Cursitor Doom wrote:
Gentlemen,
in pursuance of what is turning out to be a jinxed project (installing a
dashcam) I\'m attempting to drop 14.5V (the normal battery voltage whilst
the engine is running) to 5V for the camera. The camera draws at most
300mA so the regulator (an L7805CV) shouldn\'t find that task too much of
a struggle, since it only has to disspate just under 3 Watts by my
reckoning. I\'d have thought this reasonably large heatsink (see 20p piece
for scale comparison) would be overkill. Unfortunately it isn\'t, though.
Even with a low ambient temp of about 65\'F it gets a bit too hot to touch
after a few minutes, so once in the car in a couple of months with a
T_amb north of 100\'F, it hasn\'t a hope in hell of preventing the reg from
going up in smoke.
Apart from advising me to permanantly give up electronics, has anyone got
any constructive suggestions to make here?
TIA.
Not sure \"too hot to touch\" is a good measure, because a good conductor
of heat will feel too hot even at a modest temperature.
If a single bigger heat sink is not an option, you could use a 7809 or
7810 to drive the 7805, splitting the heat output roughly between them.
Sylvia.
There are cute little 3-pin potted switching regulators that drop into
a 7805 footprint.
I hadn\'t come across those. Cursitor might be interested in
https://www.digikey.com/en/products/detail/mornsun-america-llc/K7805M-1000R3/13168132
Sylvia.
Check this one out:
https://www.digikey.com/en/products/detail/xp-power/SRH05S12/8021461?s=N4IgTCBcDaIMoCUASAGArHAjBAugXyA
72 volts max input! I use it to drop 48 volts down to a more managable
12.
Those 70V regulators help a lot in that.
J
Jan Panteltje
Guest
On a sunny day (Sat, 08 Jan 2022 21:20:26 +0200) it happened LM
<sala.nimi@mail.com> wrote in <2sojtg1il3ind7sj8jutqcsh811dqit2vd@4ax.com>:
I just ue LM2596
needs one inductor, some caps, some resistors, it is a 150 kHz switcher, 45 V max input.
There are fixed voltage versions, but by adding resistors to the 3.3 V version feedback
you can make any output voltage > 3.3V.
<sala.nimi@mail.com> wrote in <2sojtg1il3ind7sj8jutqcsh811dqit2vd@4ax.com>:
On Tue, 04 Jan 2022 21:41:32 -0800, jlarkin@highlandsniptechnology.com
wrote:
On Wed, 5 Jan 2022 16:25:22 +1100, Sylvia Else <sylvia@email.invalid
wrote:
On 05-Jan-22 4:16 pm, jlarkin@highlandsniptechnology.com wrote:
On Wed, 5 Jan 2022 14:07:30 +1100, Sylvia Else <sylvia@email.invalid
wrote:
On 20-Apr-20 3:41 am, Cursitor Doom wrote:
Gentlemen,
in pursuance of what is turning out to be a jinxed project (installing a
dashcam) I\'m attempting to drop 14.5V (the normal battery voltage whilst
the engine is running) to 5V for the camera. The camera draws at most
300mA so the regulator (an L7805CV) shouldn\'t find that task too much of
a struggle, since it only has to disspate just under 3 Watts by my
reckoning. I\'d have thought this reasonably large heatsink (see 20p piece
for scale comparison) would be overkill. Unfortunately it isn\'t, though.
Even with a low ambient temp of about 65\'F it gets a bit too hot to touch
after a few minutes, so once in the car in a couple of months with a
T_amb north of 100\'F, it hasn\'t a hope in hell of preventing the reg from
going up in smoke.
Apart from advising me to permanantly give up electronics, has anyone got
any constructive suggestions to make here?
TIA.
Not sure \"too hot to touch\" is a good measure, because a good conductor
of heat will feel too hot even at a modest temperature.
If a single bigger heat sink is not an option, you could use a 7809 or
7810 to drive the 7805, splitting the heat output roughly between them.
Sylvia.
There are cute little 3-pin potted switching regulators that drop into
a 7805 footprint.
I hadn\'t come across those. Cursitor might be interested in
https://www.digikey.com/en/products/detail/mornsun-america-llc/K7805M-1000R3/13168132
Sylvia.
Check this one out:
https://www.digikey.com/en/products/detail/xp-power/SRH05S12/8021461?s=N4IgTCBcDaIMoCUASAGArHAjBAugXyA
72 volts max input! I use it to drop 48 volts down to a more managable
12.
I once wondered how can I get an input with widest voltage range.
Those 70V regulators help a lot in that.
I just ue LM2596
needs one inductor, some caps, some resistors, it is a 150 kHz switcher, 45 V max input.
There are fixed voltage versions, but by adding resistors to the 3.3 V version feedback
you can make any output voltage > 3.3V.
S
server
Guest
On Sat, 08 Jan 2022 19:55:42 GMT, Jan Panteltje
<pNaonStpealmtje@yahoo.com> wrote:
We use LM2576HV-ADJ, which tolerates 60 volts in and is rated for 3
amps out. It runs at 52 KHz, so needs huge L and C.
A few of our products start with a kilowatt or so of 48 volt MeanWell
supply, so we need to step down to 12 or 15 volts for secondary linear
and switching regs.
https://www.dropbox.com/s/ajmnj0j5h45lfbl/P902B_5.jpg?raw=1
--
I yam what I yam - Popeye
<pNaonStpealmtje@yahoo.com> wrote:
On a sunny day (Sat, 08 Jan 2022 21:20:26 +0200) it happened LM
sala.nimi@mail.com> wrote in <2sojtg1il3ind7sj8jutqcsh811dqit2vd@4ax.com>:
On Tue, 04 Jan 2022 21:41:32 -0800, jlarkin@highlandsniptechnology.com
wrote:
On Wed, 5 Jan 2022 16:25:22 +1100, Sylvia Else <sylvia@email.invalid
wrote:
On 05-Jan-22 4:16 pm, jlarkin@highlandsniptechnology.com wrote:
On Wed, 5 Jan 2022 14:07:30 +1100, Sylvia Else <sylvia@email.invalid
wrote:
On 20-Apr-20 3:41 am, Cursitor Doom wrote:
Gentlemen,
in pursuance of what is turning out to be a jinxed project (installing a
dashcam) I\'m attempting to drop 14.5V (the normal battery voltage whilst
the engine is running) to 5V for the camera. The camera draws at most
300mA so the regulator (an L7805CV) shouldn\'t find that task too much of
a struggle, since it only has to disspate just under 3 Watts by my
reckoning. I\'d have thought this reasonably large heatsink (see 20p piece
for scale comparison) would be overkill. Unfortunately it isn\'t, though.
Even with a low ambient temp of about 65\'F it gets a bit too hot to touch
after a few minutes, so once in the car in a couple of months with a
T_amb north of 100\'F, it hasn\'t a hope in hell of preventing the reg from
going up in smoke.
Apart from advising me to permanantly give up electronics, has anyone got
any constructive suggestions to make here?
TIA.
Not sure \"too hot to touch\" is a good measure, because a good conductor
of heat will feel too hot even at a modest temperature.
If a single bigger heat sink is not an option, you could use a 7809 or
7810 to drive the 7805, splitting the heat output roughly between them.
Sylvia.
There are cute little 3-pin potted switching regulators that drop into
a 7805 footprint.
I hadn\'t come across those. Cursitor might be interested in
https://www.digikey.com/en/products/detail/mornsun-america-llc/K7805M-1000R3/13168132
Sylvia.
Check this one out:
https://www.digikey.com/en/products/detail/xp-power/SRH05S12/8021461?s=N4IgTCBcDaIMoCUASAGArHAjBAugXyA
72 volts max input! I use it to drop 48 volts down to a more managable
12.
I once wondered how can I get an input with widest voltage range.
Those 70V regulators help a lot in that.
I just ue LM2596
needs one inductor, some caps, some resistors, it is a 150 kHz switcher, 45 V max input.
There are fixed voltage versions, but by adding resistors to the 3.3 V version feedback
you can make any output voltage > 3.3V.
We use LM2576HV-ADJ, which tolerates 60 volts in and is rated for 3
amps out. It runs at 52 KHz, so needs huge L and C.
A few of our products start with a kilowatt or so of 48 volt MeanWell
supply, so we need to step down to 12 or 15 volts for secondary linear
and switching regs.
https://www.dropbox.com/s/ajmnj0j5h45lfbl/P902B_5.jpg?raw=1
--
I yam what I yam - Popeye
L
Lasse Langwadt Christensen
Guest
lørdag den 8. januar 2022 kl. 20.57.15 UTC+1 skrev Jan Panteltje:
https://www.ebay.com/itm/353775582161
something like this is convinient for sticking on a prototype board
https://www.ebay.com/itm/224151690136
On a sunny day (Sat, 08 Jan 2022 21:20:26 +0200) it happened LM
sala...@mail.com> wrote in <2sojtg1il3ind7sj8...@4ax.com>:
On Tue, 04 Jan 2022 21:41:32 -0800, jla...@highlandsniptechnology.com
wrote:
On Wed, 5 Jan 2022 16:25:22 +1100, Sylvia Else <syl...@email.invalid
wrote:
On 05-Jan-22 4:16 pm, jla...@highlandsniptechnology.com wrote:
On Wed, 5 Jan 2022 14:07:30 +1100, Sylvia Else <syl...@email.invalid
wrote:
On 20-Apr-20 3:41 am, Cursitor Doom wrote:
Gentlemen,
in pursuance of what is turning out to be a jinxed project (installing a
dashcam) I\'m attempting to drop 14.5V (the normal battery voltage whilst
the engine is running) to 5V for the camera. The camera draws at most
300mA so the regulator (an L7805CV) shouldn\'t find that task too much of
a struggle, since it only has to disspate just under 3 Watts by my
reckoning. I\'d have thought this reasonably large heatsink (see 20p piece
for scale comparison) would be overkill. Unfortunately it isn\'t, though.
Even with a low ambient temp of about 65\'F it gets a bit too hot to touch
after a few minutes, so once in the car in a couple of months with a
T_amb north of 100\'F, it hasn\'t a hope in hell of preventing the reg from
going up in smoke.
Apart from advising me to permanantly give up electronics, has anyone got
any constructive suggestions to make here?
TIA.
Not sure \"too hot to touch\" is a good measure, because a good conductor
of heat will feel too hot even at a modest temperature.
If a single bigger heat sink is not an option, you could use a 7809 or
7810 to drive the 7805, splitting the heat output roughly between them.
Sylvia.
There are cute little 3-pin potted switching regulators that drop into
a 7805 footprint.
I hadn\'t come across those. Cursitor might be interested in
https://www.digikey.com/en/products/detail/mornsun-america-llc/K7805M-1000R3/13168132
Sylvia.
Check this one out:
https://www.digikey.com/en/products/detail/xp-power/SRH05S12/8021461?s=N4IgTCBcDaIMoCUASAGArHAjBAugXyA
72 volts max input! I use it to drop 48 volts down to a more managable
12.
I once wondered how can I get an input with widest voltage range.
Those 70V regulators help a lot in that.
I just ue LM2596
needs one inductor, some caps, some resistors, it is a 150 kHz switcher, 45 V max input.
There are fixed voltage versions, but by adding resistors to the 3.3 V version feedback
you can make any output voltage > 3.3V.
https://www.ebay.com/itm/353775582161
something like this is convinient for sticking on a prototype board
https://www.ebay.com/itm/224151690136