J308 for really-low voltage oscillator

Hey,

I am looking for a J308, but it looks like it's obsolete.

http://www.mouser.com/ProductDetail/InterFET/J308/?qs=OxRSArmBDfwrWzaWx947ZA%3D%3D

Any ideas?

I'm trying to build a low voltage oscillator that works down to about 0.15 V, basically these:

http://www.google.com/patents/US4734658

http://web.archive.org/web/20150316093734/http://neazoi.gr/energy-harvesting/index.htm

Thanks!

Michael

 

On Wednesday, March 23, 2016 at 4:07:25 PM UTC-7, John Larkin wrote:

On Wed, 23 Mar 2016 14:36:49 -0700 (PDT), mrdarrett@gmail.com wrote:

Hey,

I am looking for a J308, but it looks like it's obsolete.

http://www.mouser.com/ProductDetail/InterFET/J308/?qs=OxRSArmBDfwrWzaWx947ZA%3D%3D

Any ideas?

I'm trying to build a low voltage oscillator that works down to about 0.15 V, basically these:

http://www.google.com/patents/US4734658

http://web.archive.org/web/20150316093734/http://neazoi.gr/energy-harvesting/index.htm

Thanks!

Michael


BF862, a jfet, might work.

Ok thanks! About $0.54 each at Mouser.

http://www.mouser.com/Search/Refine.aspx?Keyword=bf862

A phemt might work better than a jfet. Transconductance can be really
high, 10x a jfet maybe.

http://www.digikey.com/product-detail/en/cel/NE3508M04-A/NE3508M04-A-ND/949555

Ooh, Digikey is out (non-stock). What is a Phemt?

And, if I'm trying to run at really low voltages (basically, wringing out all the energy out of dead AA batteries) what kind of characteristics am I looking for in a JFET?

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

Thanks,

Michael

 

On Wednesday, March 23, 2016 at 4:31:35 PM UTC-7, mrda...@gmail.com wrote:
> On Wednesday, March 23, 2016 at 4:07:25 PM UTC-7, John Larkin wrote:

....

A phemt might work better than a jfet. Transconductance can be really
high, 10x a jfet maybe.

http://www.digikey.com/product-detail/en/cel/NE3508M04-A/NE3508M04-A-ND/949555


Ooh, Digikey is out (non-stock). What is a Phemt?

Oh, never mind, I found it! It really is a thing!

https://en.wikipedia.org/wiki/High-electron-mobility_transistor

Michael

 

[John Larkin]

On Wed, 23 Mar 2016 14:36:49 -0700 (PDT), mrdarrett@gmail.com wrote:

Hey,

I am looking for a J308, but it looks like it's obsolete.

http://www.mouser.com/ProductDetail/InterFET/J308/?qs=OxRSArmBDfwrWzaWx947ZA%3D%3D

Any ideas?

I'm trying to build a low voltage oscillator that works down to about 0.15 V, basically these:

http://www.google.com/patents/US4734658

http://web.archive.org/web/20150316093734/http://neazoi.gr/energy-harvesting/index.htm

Thanks!

Michael

BF862, a jfet, might work.

A phemt might work better than a jfet. Transconductance can be really
high, 10x a jfet maybe.

http://www.digikey.com/product-detail/en/cel/NE3508M04-A/NE3508M04-A-ND/949555



--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[George Herold]

On Wednesday, March 23, 2016 at 5:36:53 PM UTC-4, mrda...@gmail.com wrote:

Hey,

I am looking for a J308, but it looks like it's obsolete.

http://www.mouser.com/ProductDetail/InterFET/J308/?qs=OxRSArmBDfwrWzaWx947ZA%3D%3D

Any ideas?

I'm trying to build a low voltage oscillator that works down to about 0.15 V, basically these:

http://www.google.com/patents/US4734658

http://web.archive.org/web/20150316093734/http://neazoi.gr/energy-harvesting/index.htm

Thanks!

Michael

octoparts?
https://octopart.com/search?q=J308%20jfet&start=0

George H.

 

On Thursday, March 24, 2016 at 5:07:12 AM UTC-7, Bob Masta wrote:

On Wed, 23 Mar 2016 16:31:27 -0700 (PDT),
mrdarrett@gmail.com wrote:

snip

And, if I'm trying to run at really low voltages (basically, wringing out all the energy out of dead AA batteries) what kind of characteristics am I looking for in a JFET?

Another way to wring more energy out is to put 'em in
series. Then you need an efficient way to cut down the
voltage during the early part of the discharge curve.

That works, until one battery decides to become a traffic jam and prevent any further current from passing

Reminds me of a science day at my son's school. His group was playing with maybe 10 9V batteries in series to get impressive sparks. Then the sparks got weaker. So I suggested that they test the batteries, remove the weakest one, and try again. They found a dead one, removed it and re-assembled the pile. Huge sparks again!

Thanks,

Michael

Back in the Olden Days when Heavy Duty (carbob-zinc)
batteries were cheaper (and lighter) per watt-hour than
alkalines, I used 4 of them to drive a 3-volt bulb for a
caving headlamp, with PWM to control the power. Turned out
to be trickier than I had anticipated, since (of course) the
power is proportional to V^2.

Oh, cool! I remember the days when my dad would collect Radio Shack free carbon-zinc battery club cards, and we'd always show up and get a few C or D cells

Best regards,


Bob Masta

DAQARTA v9.00
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, Pitch Track, Pitch-to-MIDI
FREE 8-channel Signal Generator, DaqMusiq generator
Science with your sound card!

Thanks!

Michael

 

On Thursday, March 24, 2016 at 6:00:19 AM UTC-7, George Herold wrote:

On Wednesday, March 23, 2016 at 5:36:53 PM UTC-4, mrda...@gmail.com wrote:
Hey,

I am looking for a J308, but it looks like it's obsolete.

http://www.mouser.com/ProductDetail/InterFET/J308/?qs=OxRSArmBDfwrWzaWx947ZA%3D%3D

Any ideas?

I'm trying to build a low voltage oscillator that works down to about 0.15 V, basically these:

http://www.google.com/patents/US4734658

http://web.archive.org/web/20150316093734/http://neazoi.gr/energy-harvesting/index.htm

Thanks!

Michael

octoparts?
https://octopart.com/search?q=J308%20jfet&start=0

George H.

Oh. My. Goodness. THANKS!

Michael

 

On Thursday, March 24, 2016 at 7:36:42 AM UTC-7, John Larkin wrote:
> On Wed, 23 Mar 2016 16:31:27 -0700 (PDT), mrdarrett@gmail.com wrote:

....

And, if I'm trying to run at really low voltages (basically, wringing out all the energy out of dead AA batteries) what kind of characteristics am I looking for in a JFET?


High transconductance and fairly high Idss, mostly.

You want to modulate a bunch of drain current with a small gate swing,
but how much gate swing is available depends on the circuit.

A nearly dead (low voltage) battery won't have much energy left.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

Okie doke. Thanks!

Michael

 

[Bob Masta]

On Wed, 23 Mar 2016 16:31:27 -0700 (PDT),
mrdarrett@gmail.com wrote:

<snip>

And, if I'm trying to run at really low voltages (basically, wringing out all the energy out of dead AA batteries) what kind of characteristics am I looking for in a JFET?

Another way to wring more energy out is to put 'em in
series. Then you need an efficient way to cut down the
voltage during the early part of the discharge curve.

Back in the Olden Days when Heavy Duty (carbob-zinc)
batteries were cheaper (and lighter) per watt-hour than
alkalines, I used 4 of them to drive a 3-volt bulb for a
caving headlamp, with PWM to control the power. Turned out
to be trickier than I had anticipated, since (of course) the
power is proportional to V^2.

Best regards,


Bob Masta

DAQARTA v9.00
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, Pitch Track, Pitch-to-MIDI
FREE 8-channel Signal Generator, DaqMusiq generator
Science with your sound card!

 

[John Larkin]

On Wed, 23 Mar 2016 16:31:27 -0700 (PDT), mrdarrett@gmail.com wrote:

On Wednesday, March 23, 2016 at 4:07:25 PM UTC-7, John Larkin wrote:
On Wed, 23 Mar 2016 14:36:49 -0700 (PDT), mrdarrett@gmail.com wrote:

Hey,

I am looking for a J308, but it looks like it's obsolete.

http://www.mouser.com/ProductDetail/InterFET/J308/?qs=OxRSArmBDfwrWzaWx947ZA%3D%3D

Any ideas?

I'm trying to build a low voltage oscillator that works down to about 0.15 V, basically these:

http://www.google.com/patents/US4734658

http://web.archive.org/web/20150316093734/http://neazoi.gr/energy-harvesting/index.htm

Thanks!

Michael


BF862, a jfet, might work.


Ok thanks! About $0.54 each at Mouser.

http://www.mouser.com/Search/Refine.aspx?Keyword=bf862



A phemt might work better than a jfet. Transconductance can be really
high, 10x a jfet maybe.

http://www.digikey.com/product-detail/en/cel/NE3508M04-A/NE3508M04-A-ND/949555


Ooh, Digikey is out (non-stock). What is a Phemt?

And, if I'm trying to run at really low voltages (basically, wringing out all the energy out of dead AA batteries) what kind of characteristics am I looking for in a JFET?

High transconductance and fairly high Idss, mostly.

You want to modulate a bunch of drain current with a small gate swing,
but how much gate swing is available depends on the circuit.

A nearly dead (low voltage) battery won't have much energy left.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

On Thursday, March 24, 2016 at 11:49:05 AM UTC-7, Phil Hobbs wrote:

....

pHEMTs are amazing parts for some things, but I'm pretty sure that
John's pulling your leg about using one in a Joule Thief. The slowest
pHEMTs are about 10 GHz iirc. They also have seriously crummy Early
voltages, so they might not work as well as a JFET when V_DS gets down
to the hundreds of millivolts.

The J308/309/310 are pretty well the same FET with different I_DSS
limits, iirc. You can still get J309s with no worries.

(My fave pHEMT circuit fragment is a SiGe:C BJT as a combination cascode
and bootstrap on the pHEMT's drain. I've talked about that in SED quite
a bit in the last couple of years.)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

Oh ok, thanks!

Michael

 

[Phil Hobbs]

On 03/23/2016 07:34 PM, mrdarrett@gmail.com wrote:

On Wednesday, March 23, 2016 at 4:31:35 PM UTC-7, mrda...@gmail.com wrote:
On Wednesday, March 23, 2016 at 4:07:25 PM UTC-7, John Larkin wrote:

...

A phemt might work better than a jfet. Transconductance can be really
high, 10x a jfet maybe.

http://www.digikey.com/product-detail/en/cel/NE3508M04-A/NE3508M04-A-ND/949555


Ooh, Digikey is out (non-stock). What is a Phemt?


Oh, never mind, I found it! It really is a thing!

https://en.wikipedia.org/wiki/High-electron-mobility_transistor

Michael

pHEMTs are amazing parts for some things, but I'm pretty sure that
John's pulling your leg about using one in a Joule Thief. The slowest
pHEMTs are about 10 GHz iirc. They also have seriously crummy Early
voltages, so they might not work as well as a JFET when V_DS gets down
to the hundreds of millivolts.

The J308/309/310 are pretty well the same FET with different I_DSS
limits, iirc. You can still get J309s with no worries.

(My fave pHEMT circuit fragment is a SiGe:C BJT as a combination cascode
and bootstrap on the pHEMT's drain. I've talked about that in SED quite
a bit in the last couple of years.)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

On Thursday, March 24, 2016 at 3:45:08 PM UTC-7, John Larkin wrote:

On Thu, 24 Mar 2016 14:49:02 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 03/23/2016 07:34 PM, mrdarrett@gmail.com wrote:
On Wednesday, March 23, 2016 at 4:31:35 PM UTC-7, mrda...@gmail.com wrote:
On Wednesday, March 23, 2016 at 4:07:25 PM UTC-7, John Larkin wrote:

...

A phemt might work better than a jfet. Transconductance can be really
high, 10x a jfet maybe.

http://www.digikey.com/product-detail/en/cel/NE3508M04-A/NE3508M04-A-ND/949555


Ooh, Digikey is out (non-stock). What is a Phemt?


Oh, never mind, I found it! It really is a thing!

https://en.wikipedia.org/wiki/High-electron-mobility_transistor

Michael


pHEMTs are amazing parts for some things, but I'm pretty sure that
John's pulling your leg about using one in a Joule Thief. The slowest
pHEMTs are about 10 GHz iirc. They also have seriously crummy Early
voltages, so they might not work as well as a JFET when V_DS gets down
to the hundreds of millivolts.

I was serious. Rds-on is about 6 ohms for that NEC part at zero gate
voltage, and transconductance is outrageous compared to a jfet or a
depletion mosfet. Just what you want to power some oscillator thing
from a thermocouple or some such millivolt source.

Oh ok! The pHEMT is $1.50 or so from Mouser. I'll try both it and the J308-215.

Mouser part numbers:
771-PMBFJ308215
551-NE3508M04-A


Thanks guys!

Michael

 

[Sjouke Burry]

On 24.03.16 15:36, John Larkin wrote:

On Wed, 23 Mar 2016 16:31:27 -0700 (PDT), mrdarrett@gmail.com wrote:

On Wednesday, March 23, 2016 at 4:07:25 PM UTC-7, John Larkin wrote:
On Wed, 23 Mar 2016 14:36:49 -0700 (PDT), mrdarrett@gmail.com wrote:

Hey,

I am looking for a J308, but it looks like it's obsolete.

http://www.mouser.com/ProductDetail/InterFET/J308/?qs=OxRSArmBDfwrWzaWx947ZA%3D%3D

Any ideas?

I'm trying to build a low voltage oscillator that works down to about 0.15 V, basically these:

http://www.google.com/patents/US4734658

http://web.archive.org/web/20150316093734/http://neazoi.gr/energy-harvesting/index.htm

Thanks!

Michael


BF862, a jfet, might work.


Ok thanks! About $0.54 each at Mouser.

http://www.mouser.com/Search/Refine.aspx?Keyword=bf862



A phemt might work better than a jfet. Transconductance can be really
high, 10x a jfet maybe.

http://www.digikey.com/product-detail/en/cel/NE3508M04-A/NE3508M04-A-ND/949555


Ooh, Digikey is out (non-stock). What is a Phemt?

And, if I'm trying to run at really low voltages (basically, wringing out all the energy out of dead AA batteries) what kind of characteristics am I looking for in a JFET?


High transconductance and fairly high Idss, mostly.

You want to modulate a bunch of drain current with a small gate swing,
but how much gate swing is available depends on the circuit.

A nearly dead (low voltage) battery won't have much energy left.

Putting a 1-10 farad supercap across the battery might be
the best way to get most power out of the battery.
The cap gets a trickle charge from the battery, and can then
for some minutes supply low loss power.

 

[John Larkin]

On Thu, 24 Mar 2016 14:49:02 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 03/23/2016 07:34 PM, mrdarrett@gmail.com wrote:
On Wednesday, March 23, 2016 at 4:31:35 PM UTC-7, mrda...@gmail.com wrote:
On Wednesday, March 23, 2016 at 4:07:25 PM UTC-7, John Larkin wrote:

...

A phemt might work better than a jfet. Transconductance can be really
high, 10x a jfet maybe.

http://www.digikey.com/product-detail/en/cel/NE3508M04-A/NE3508M04-A-ND/949555


Ooh, Digikey is out (non-stock). What is a Phemt?


Oh, never mind, I found it! It really is a thing!

https://en.wikipedia.org/wiki/High-electron-mobility_transistor

Michael


pHEMTs are amazing parts for some things, but I'm pretty sure that
John's pulling your leg about using one in a Joule Thief. The slowest
pHEMTs are about 10 GHz iirc. They also have seriously crummy Early
voltages, so they might not work as well as a JFET when V_DS gets down
to the hundreds of millivolts.

I was serious. Rds-on is about 6 ohms for that NEC part at zero gate
voltage, and transconductance is outrageous compared to a jfet or a
depletion mosfet. Just what you want to power some oscillator thing
from a thermocouple or some such millivolt source.

The J308/309/310 are pretty well the same FET with different I_DSS
limits, iirc. You can still get J309s with no worries.

(My fave pHEMT circuit fragment is a SiGe:C BJT as a combination cascode
and bootstrap on the pHEMT's drain. I've talked about that in SED quite
a bit in the last couple of years.)

Cheers

Phil Hobbs

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[Mark Zenier]

In article <543334f8-41d1-4e93-a5e0-9d229a27e228@googlegroups.com>,
<mrdarrett@gmail.com> wrote:

Hey,

I am looking for a J308, but it looks like it's obsolete.
http://www.mouser.com/ProductDetail/InterFET/J308/?qs=OxRSArmBDfwrWzaWx947ZA%3D%3D
Any ideas?
I'm trying to build a low voltage oscillator that works down to about
0.15 V, basically these:
http://www.google.com/patents/US4734658
http://web.archive.org/web/20150316093734/http://neazoi.gr/energy-harvesting/index.htm

As I remember (my databooks are buried too deep to dig it out), the
J308, J309, and J310 are on the same datasheet and are basically the
same thing with slightly different specs. I don't remember if the
specs get tighter as the number goes up. Try looking for a J310.


Mark Zenier mzenier@eskimo.com
Googleproofaddress(account:mzenier provider:eskimo domain:com)

 

On Friday, March 25, 2016 at 6:29:53 AM UTC-7, Mark Zenier wrote:

In article <543334f8-41d1-4e93-a5e0-9d229a27e228@googlegroups.com>,
mrdarrett@gmail.com> wrote:
Hey,

I am looking for a J308, but it looks like it's obsolete.
http://www.mouser.com/ProductDetail/InterFET/J308/?qs=OxRSArmBDfwrWzaWx947ZA%3D%3D
Any ideas?
I'm trying to build a low voltage oscillator that works down to about
0.15 V, basically these:
http://www.google.com/patents/US4734658
http://web.archive.org/web/20150316093734/http://neazoi.gr/energy-harvesting/index.htm

As I remember (my databooks are buried too deep to dig it out), the
J308, J309, and J310 are on the same datasheet and are basically the
same thing with slightly different specs. I don't remember if the
specs get tighter as the number goes up. Try looking for a J310.


Mark Zenier mzenier@eskimo.com
Googleproofaddress(account:mzenier provider:eskimo domain:com)

I think the J308 allows higher current, but needs a slightly higher voltage to work, than the J310. From the second link I posted:

http://web.archive.org/web/20150316093734/http://neazoi.gr/energy-harvesting/index.htm

"Conclusion

This patent circuit is absolutely fabulous. I would use the J310 in applications that require a small current from an ultra low voltage source, like charging a supercap slowly. If an input voltage of 70mV more can be tolerated and if the source can provide enough current, I would definitely use the J108, as it is able to provide much more current. The LED really shines like the Joule thief circuit, but starting reliably at a much lower voltage!"

Thanks,

Michael

 

[Phil Hobbs]

On 03/24/2016 06:45 PM, John Larkin wrote:

On Thu, 24 Mar 2016 14:49:02 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 03/23/2016 07:34 PM, mrdarrett@gmail.com wrote:
On Wednesday, March 23, 2016 at 4:31:35 PM UTC-7, mrda...@gmail.com wrote:
On Wednesday, March 23, 2016 at 4:07:25 PM UTC-7, John Larkin wrote:

...

A phemt might work better than a jfet. Transconductance can be really
high, 10x a jfet maybe.

http://www.digikey.com/product-detail/en/cel/NE3508M04-A/NE3508M04-A-ND/949555


Ooh, Digikey is out (non-stock). What is a Phemt?


Oh, never mind, I found it! It really is a thing!

https://en.wikipedia.org/wiki/High-electron-mobility_transistor

Michael


pHEMTs are amazing parts for some things, but I'm pretty sure that
John's pulling your leg about using one in a Joule Thief. The slowest
pHEMTs are about 10 GHz iirc. They also have seriously crummy Early
voltages, so they might not work as well as a JFET when V_DS gets down
to the hundreds of millivolts.

I was serious. Rds-on is about 6 ohms for that NEC part at zero gate
voltage, and transconductance is outrageous compared to a jfet or a
depletion mosfet. Just what you want to power some oscillator thing
from a thermocouple or some such millivolt source.

Okay, my mistake. (That "lunatic fringe" thing again.)

The transconductance is nice and high at fixed bias, true. However, the
Avago parts have the wimpiest drain impedance I've ever seen--something
like 160 ohms. You can't even use them as source followers unless you
bootstrap the drain. The Skyworks parts (SKY65050) are quite a bit
better, but still not even as good as a JFET. I haven't tried the NEC
parts.

It would be entertaining to try using a 14-GHz part on a white plastic
breadboard. OTOH they're surprisingly stable for such fast and quiet
devices--a lot more stable than the SiGe parts!

Cheers

Phil Hobbs

 

On Friday, March 25, 2016 at 1:33:49 PM UTC-7, amdx wrote:

On 3/23/2016 6:07 PM, John Larkin wrote:
On Wed, 23 Mar 2016 14:36:49 -0700 (PDT), mrdarrett@gmail.com wrote:

Hey,

I am looking for a J308, but it looks like it's obsolete.

http://www.mouser.com/ProductDetail/InterFET/J308/?qs=OxRSArmBDfwrWzaWx947ZA%3D%3D

Any ideas?

I'm trying to build a low voltage oscillator that works down to about 0.15 V, basically these:

http://www.google.com/patents/US4734658

http://web.archive.org/web/20150316093734/http://neazoi.gr/energy-harvesting/index.htm

Thanks!

Michael

I've posted this before, author says the best iteration will start
oscillating at 7mV 1.1Ma. He is not drawing power from the circuit, so...
Oops, he got it down to 5.5Mv 0.41 Ma, he moved the scope to a lower
impedance point, it was loading his circuit.

http://www.dicks-website.eu/fetosc/enindex.htm

Mikek

Thanks!

That reminds me... I have a spare ignition coil in the garage somewhere...

Michael

 

[amdx]

On 3/23/2016 6:07 PM, John Larkin wrote:

On Wed, 23 Mar 2016 14:36:49 -0700 (PDT), mrdarrett@gmail.com wrote:

Hey,

I am looking for a J308, but it looks like it's obsolete.

http://www.mouser.com/ProductDetail/InterFET/J308/?qs=OxRSArmBDfwrWzaWx947ZA%3D%3D

Any ideas?

I'm trying to build a low voltage oscillator that works down to about 0.15 V, basically these:

http://www.google.com/patents/US4734658

http://web.archive.org/web/20150316093734/http://neazoi.gr/energy-harvesting/index.htm

Thanks!

Michael

I've posted this before, author says the best iteration will start
oscillating at 7mV 1.1Ma. He is not drawing power from the circuit, so...
Oops, he got it down to 5.5Mv 0.41 Ma, he moved the scope to a lower
impedance point, it was loading his circuit.

> http://www.dicks-website.eu/fetosc/enindex.htm

Mikek