ohm meter battery

[Michael A. Terrell]

Trevor Wilson wrote:

On 20/03/2014 3:16 PM, captainvideo462009@gmail.com wrote:
I found this circuit somewhere, (I can't remember) to replace the 1.50 volt battery in a VTVM. I have an RCA WV98C Senior Voltohmyst VTVM that is in perfect condition but doesn't get used very often. This battery retrofit circuit takes power from the 6.30 volt filament transformer and is built around an LM317. With a trim pot you set it for 1.55 volts and you never have to change a battery again. It also needs to occupy an area no larger than the battery presently does.

As much as I like keeping things original, I'm worried that the battery is going to leak and rot the inside of the unit. I was going to build the circuit but it occurred to me that I should probably be concerned about the current that the LM317 will be dissipating when the meter is used on the low ohms range. Does anyone have a feel for the size that an adequate sized heat sink should be in order to handle this? Thanks, Lenny


**Crazy idea, Lenny:

Move yourself into the 1970s and buy yourself a digital multimeter. Most
of them operate on a 9 Volt battery. Replace the battery every year and
you'll be sweet. Even a US$20.00 meter will give you a vast improvement
in every performance parameter over your ancient POS, which is likely
well outside it's original performance specs.

Like this one:

http://au.mouser.com/ProductDetail/Extech/MN35-WITH-TEMP-PROBE/?qs=sGAEpiMZZMtySgZ4QeaOR6vEN3IEHJ9OqaRLKRQ5wis%3d

One of my meters measures the usual Volts, Amps & Ohms AND light
intensity, sound pressure level, relative humidity and transistor gain.
I recall that it cost me AUS$50.00.

I have a nice collection of analogue meters (I recently acquired a
beautiful AVO 8 Mk7), but I never use them anymore.

Go digital. You will not be sorry.

Yes, he will. A VTVM has a 1 Meg resistor in the probe for DC
measurements, to keep it from affecting the circuit being tested. The
capacitance of a set of meter leads on a DVM will screw up a lot of high
impedance circuits.


Here is one of many simple conversions to replace the battery with a
regulated DC supply. You only need a few mA for the Ohm meter function
in a VTVM. I did this to several VTVMs back in the '70s.

View in a fixed-width font such as Courier.

+---+ 1N4001 TIP29
| | +-----++ C E 1.5VDC
| +---+ |+---+-----+-----\ /---------+-------o
| | +-----++ | | \ / |
6.3VAC| |+ +++ --+-- |
| | -+- | | B | |
| | 50uF -+- | | +-----+ |
| +---+ | | |1k | | |+
| | | -+- +++ | | -+-
+---+ | Gnd | | | -+-
-+- +--------+ | | 10uF
Gnd | |+ |
| -+- |
+++ -+- |
| | | 10uF |
1N4001 | | | |
+-+ | -+-
+++ | Gnd
| |
+-+ |
| | -+-
1N4001 | | Gnd
+-+
+++
|
-+-
Gnd


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

 

On Thursday, March 20, 2014 12:16:03 AM UTC-4, captainvi...@gmail.com wrote:

I found this circuit somewhere, (I can't remember) to replace the 1.50 volt battery in a VTVM. I have an RCA WV98C Senior Voltohmyst VTVM that is in perfect condition but doesn't get used very often. This battery retrofit circuit takes power from the 6.30 volt filament transformer and is built around an LM317. With a trim pot you set it for 1.55 volts and you never have to change a battery again. It also needs to occupy an area no larger than the battery presently does.



As much as I like keeping things original, I'm worried that the battery is going to leak and rot the inside of the unit. I was going to build the circuit but it occurred to me that I should probably be concerned about the current that the LM317 will be dissipating when the meter is used on the low ohms range. Does anyone have a feel for the size that an adequate sized heat sink should be in order to handle this? Thanks, Lenny

I do own several digital voltmeters and they do have their place. You can't beat a digital for making precise measurements. But there is a bit of a sentimental value here too. I built this meter from a kit when I was a kid in 1963. Since then I've repaired a lot of TV sets and other things with it over the years, and although I don't use it much anymore it's nice to still be able to when the need arises. So just where the hell do you come off insulting me?

I'm just curious now. Did you ever try to peak or null a circuit with a digital? It's a pain in the ass. How about looking for a change in logic state? I prefer seeing an immediate change rather than watching a decay. Why don't you try going on the grid of a tube with a low impedance meter and see where that gets you? Mine has an 11 meg ohm impedance. It won't load a vacuum tube circuit. So much for my piece of shit meter, huh?

But I have a better idea Trevor. Why don't you take your prize digital you've raved about and stick it in your ass? That way you'll never lose it, and it will always be available. Lenny

 

[Trevor Wilson]

On 21/03/2014 2:04 PM, captainvideo462009@gmail.com wrote:

On Thursday, March 20, 2014 12:16:03 AM UTC-4, captainvi...@gmail.com
wrote:
I found this circuit somewhere, (I can't remember) to replace the
1.50 volt battery in a VTVM. I have an RCA WV98C Senior Voltohmyst
VTVM that is in perfect condition but doesn't get used very often.
This battery retrofit circuit takes power from the 6.30 volt
filament transformer and is built around an LM317. With a trim pot
you set it for 1.55 volts and you never have to change a battery
again. It also needs to occupy an area no larger than the battery
presently does.



As much as I like keeping things original, I'm worried that the
battery is going to leak and rot the inside of the unit. I was
going to build the circuit but it occurred to me that I should
probably be concerned about the current that the LM317 will be
dissipating when the meter is used on the low ohms range. Does
anyone have a feel for the size that an adequate sized heat sink
should be in order to handle this? Thanks, Lenny

I do own several digital voltmeters and they do have their place. You
can't beat a digital for making precise measurements. But there is a
bit of a sentimental value here too. I built this meter from a kit
when I was a kid in 1963. Since then I've repaired a lot of TV sets
and other things with it over the years, and although I don't use it
much anymore it's nice to still be able to when the need arises. So
just where the hell do you come off insulting me?

**Who insulted you and how?

I understand sentimental attachments. I still have my first multimeter.
My dad gave it to me. A Sanwa. I never use it, of course. Same deal with
my AVO 8. I bought it because I always wanted one, certainly not because
I needed it. I have some other, quite exotic and rare meters too. I
still prefer my bench meter and my Fluke.

I'm just curious now. Did you ever try to peak or null a circuit with
a digital?

**Yes. It's a doddle. Both my regular digital meters have a fast bar
graph display, along with the regular digital one. Perfect for those
times when you need to see what is happening quickly.


It's a pain in the ass. How about looking for a change in
> logic state?

**Same as above.

I prefer seeing an immediate change rather than watching

a decay. Why don't you try going on the grid of a tube with a low
impedance meter and see where that gets you? Mine has an 11 meg ohm
impedance. It won't load a vacuum tube circuit. So much for my piece
of shit meter, huh?

**My Fluke 85 has an input impedance of 10 MOhm. The bench meter has in
input impedance of 20 MOhm. Plenty high enough for the vast majority of
applications. I have a 100 MOHm, shop built probe somewhere around the
place, for the odd occasion when I require very high impedance/ high
Voltage measurements.

But I have a better idea Trevor. Why don't you take your prize
digital you've raved about and stick it in your ass? That way you'll
never lose it, and it will always be available. Lenny

**I started using digital meters back in 1975 (Fluke). I didn't much
care for them. It took me many years to wean myself off an analogue
meter. Once weaned off them, I've never looked back. Analogue meters are
cool, but for day to day use, nothing beats a digital meter.


--
Trevor Wilson www.rageaudio.com.au

 

[Mark Zacharias]

"Trevor Wilson" <trevor@SPAMBLOCKrageaudio.com.au> wrote in message
news:bp26o3FhktbU1@mid.individual.net...

On 21/03/2014 2:04 PM, captainvideo462009@gmail.com wrote:
On Thursday, March 20, 2014 12:16:03 AM UTC-4, captainvi...@gmail.com
wrote:
I found this circuit somewhere, (I can't remember) to replace the
1.50 volt battery in a VTVM. I have an RCA WV98C Senior Voltohmyst
VTVM that is in perfect condition but doesn't get used very often.
This battery retrofit circuit takes power from the 6.30 volt
filament transformer and is built around an LM317. With a trim pot
you set it for 1.55 volts and you never have to change a battery
again. It also needs to occupy an area no larger than the battery
presently does.



As much as I like keeping things original, I'm worried that the
battery is going to leak and rot the inside of the unit. I was
going to build the circuit but it occurred to me that I should
probably be concerned about the current that the LM317 will be
dissipating when the meter is used on the low ohms range. Does
anyone have a feel for the size that an adequate sized heat sink
should be in order to handle this? Thanks, Lenny

I do own several digital voltmeters and they do have their place. You
can't beat a digital for making precise measurements. But there is a
bit of a sentimental value here too. I built this meter from a kit
when I was a kid in 1963. Since then I've repaired a lot of TV sets
and other things with it over the years, and although I don't use it
much anymore it's nice to still be able to when the need arises. So
just where the hell do you come off insulting me?

**Who insulted you and how?

I understand sentimental attachments. I still have my first multimeter. My
dad gave it to me. A Sanwa. I never use it, of course. Same deal with my
AVO 8. I bought it because I always wanted one, certainly not because I
needed it. I have some other, quite exotic and rare meters too. I still
prefer my bench meter and my Fluke.


I'm just curious now. Did you ever try to peak or null a circuit with
a digital?

**Yes. It's a doddle. Both my regular digital meters have a fast bar graph
display, along with the regular digital one. Perfect for those times when
you need to see what is happening quickly.


It's a pain in the ass. How about looking for a change in
logic state?

**Same as above.

I prefer seeing an immediate change rather than watching
a decay. Why don't you try going on the grid of a tube with a low
impedance meter and see where that gets you? Mine has an 11 meg ohm
impedance. It won't load a vacuum tube circuit. So much for my piece
of shit meter, huh?

**My Fluke 85 has an input impedance of 10 MOhm. The bench meter has in
input impedance of 20 MOhm. Plenty high enough for the vast majority of
applications. I have a 100 MOHm, shop built probe somewhere around the
place, for the odd occasion when I require very high impedance/ high
Voltage measurements.


But I have a better idea Trevor. Why don't you take your prize
digital you've raved about and stick it in your ass? That way you'll
never lose it, and it will always be available. Lenny


**I started using digital meters back in 1975 (Fluke). I didn't much care
for them. It took me many years to wean myself off an analogue meter. Once
weaned off them, I've never looked back. Analogue meters are cool, but for
day to day use, nothing beats a digital meter.


--
Trevor Wilson www.rageaudio.com.au

I collect them - analog and digital both. My biggest problem is giving each
of them enough love.
The analogs are mostly used for quick resistance checks, popping speakers,
small DC motors, etc. Digitals don't push enough current through the load on
resistance function for those tasks.

Voltage readings almost always rate a Fluke or Agilent.

Mark Z.

 

[dave]

On 03/20/2014 01:30 AM, William Sommerwerck wrote:

wrote in message
news:18841ca2-bf92-4b12-875d-2de16b053998@googlegroups.com...

As much as I like keeping things original, I'm worried that
the battery is going to leak and rot the inside of the unit.

Only if you use a carbon-zinc cell. An alkaline cell should be fine.

Unless it's a Duracell!

https://duckduckgo.com/?t=lm&q=leaky+duracell

 

[Phil Hobbs]

On 03/20/2014 05:03 PM, Trevor Wilson wrote:

On 20/03/2014 3:16 PM, captainvideo462009@gmail.com wrote:
I found this circuit somewhere, (I can't remember) to replace the 1.50
volt battery in a VTVM. I have an RCA WV98C Senior Voltohmyst VTVM
that is in perfect condition but doesn't get used very often. This
battery retrofit circuit takes power from the 6.30 volt filament
transformer and is built around an LM317. With a trim pot you set it
for 1.55 volts and you never have to change a battery again. It also
needs to occupy an area no larger than the battery presently does.

As much as I like keeping things original, I'm worried that the
battery is going to leak and rot the inside of the unit. I was going
to build the circuit but it occurred to me that I should probably be
concerned about the current that the LM317 will be dissipating when
the meter is used on the low ohms range. Does anyone have a feel for
the size that an adequate sized heat sink should be in order to handle
this? Thanks, Lenny


**Crazy idea, Lenny:

Move yourself into the 1970s and buy yourself a digital multimeter. Most
of them operate on a 9 Volt battery. Replace the battery every year and
you'll be sweet. Even a US$20.00 meter will give you a vast improvement
in every performance parameter over your ancient POS, which is likely
well outside it's original performance specs.


Like this one:

http://au.mouser.com/ProductDetail/Extech/MN35-WITH-TEMP-PROBE/?qs=sGAEpiMZZMtySgZ4QeaOR6vEN3IEHJ9OqaRLKRQ5wis%3d


One of my meters measures the usual Volts, Amps & Ohms AND light
intensity, sound pressure level, relative humidity and transistor gain.
I recall that it cost me AUS$50.00.

I have a nice collection of analogue meters (I recently acquired a
beautiful AVO 8 Mk7), but I never use them anymore.

AVO went south after the Mk IV, which is a thing of great beauty. (My
Mk IV came from the collection of a guy who also collected and restored
antique Rollses.)

Go digital. You will not be sorry.

Your garden variety DMM isn't much use above a kilohertz, though.

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

 

[chuck]

On Thu, 20 Mar 2014 10:24:18 -0700, "William Sommerwerck"
<grizzledgeezer@comcast.net> wrote:

"OldGuy" wrote in message news:lgf6h2$2v07$1@adenine.netfront.net...

Duracell is just as bad as any other.
Expensive Mamiya camera motor drive corroded, flashlight ruined, Nikon flash
corroded, etc (as they say much much more) ...
Also true for 9V duracells. They all leak! corrode!
Impossible to clean!
I had to grind off corrosion with a diamond tip rotary tool where I
could get at it. The flashlight was a total loss since I could not get
the batteries out!
no solvent worked!
Tried CLR, straight white vinegar, etc.

I've been using alkaline batteries for decades (including nicads and NiMHs,
which are also alkaline), and have not had these sorts of problems. Yes, I
have had leakage. But it's been uncommon, and in only one case was the contact
badly damaged.

I have a Sony TFM-117WB with four Duracell C cells in it. They've been there
over a year. I checked them the other day, and they were fine.

I have never seen a 9V battery, of any chemistry, from any manufacturer, leak.

Duracell used to guarantee that their cells wouldn't leak, and would replace
or repaire damaged products. In one case, a dictating machine was cosmetically
damaged by leakage, and Duracell made good on the guarantee.

I have had both Energiser and Duracell 9 volt batteries leak. Inside
there are multiple cells thinner than a AAA battery. Usually the
liquid oozes up through the terminals which destroys the battery plug.

 

On Thursday, March 20, 2014 12:16:03 AM UTC-4, captainvi...@gmail.com wrote:

I found this circuit somewhere, (I can't remember) to replace the 1.50 volt battery in a VTVM. I have an RCA WV98C Senior Voltohmyst VTVM that is in perfect condition but doesn't get used very often. This battery retrofit circuit takes power from the 6.30 volt filament transformer and is built around an LM317. With a trim pot you set it for 1.55 volts and you never have to change a battery again. It also needs to occupy an area no larger than the battery presently does.



As much as I like keeping things original, I'm worried that the battery is going to leak and rot the inside of the unit. I was going to build the circuit but it occurred to me that I should probably be concerned about the current that the LM317 will be dissipating when the meter is used on the low ohms range. Does anyone have a feel for the size that an adequate sized heat sink should be in order to handle this? Thanks, Lenny

Besides the things I've already mentioned regarding digital vs. analog, I've tried checking transistors and diodes with a digital, and I suppose that you can do it but perhaps it's because I've been doing this all my life with something like a 260, trying to do this with a digital drives me nuts. And Trevor you asked how you insulted me. You referred to my meter as a "piece of shit". You've never used it nor have you ever seen it. So where the hell did that come from? You may have your own opinions but there was no reason for that comment. Lenny

 

[whit3rd]

On Thursday, March 20, 2014 10:44:20 AM UTC-7, William Sommerwerck wrote:

"John Robertson" wrote in message

news:hf6dndiO65hnvrbOnZ2dnUVZ5tudnZ2d@giganews.com...

Actually considering that the battery leaks an alkaline, I can only imagine
that using additional alkaline will only make matters worse.

He's trying to unstick the battery. You want something that will dissolve an
alkalai -- another alkali.

I'm not sure that's relevant: the alkali (usually potassium hydroxide) will have
corroded the aluminum, and you cannot dissolve the corrosion!

There's a few options for removing batteries in this situation, including
lathe-and-boring-tool, but I'd trash the flashlight.

 

On Thursday, March 20, 2014 12:16:03 AM UTC-4, captainvi...@gmail.com wrote:

I found this circuit somewhere, (I can't remember) to replace the 1.50 volt battery in a VTVM. I have an RCA WV98C Senior Voltohmyst VTVM that is in perfect condition but doesn't get used very often. This battery retrofit circuit takes power from the 6.30 volt filament transformer and is built around an LM317. With a trim pot you set it for 1.55 volts and you never have to change a battery again. It also needs to occupy an area no larger than the battery presently does.



As much as I like keeping things original, I'm worried that the battery is going to leak and rot the inside of the unit. I was going to build the circuit but it occurred to me that I should probably be concerned about the current that the LM317 will be dissipating when the meter is used on the low ohms range. Does anyone have a feel for the size that an adequate sized heat sink should be in order to handle this? Thanks, Lenny

I finally found the Website where I originally found the circuit. I liked the second schematic. It's isolated from chassis ground. Here's the link:

http://mikeyancey.com/VTVM_battery_eliminator.php

 

[Michael Black]

On Fri, 21 Mar 2014, Trevor Wilson wrote:

**I started using digital meters back in 1975 (Fluke). I didn't much care for
them. It took me many years to wean myself off an analogue meter. Once weaned
off them, I've never looked back. Analogue meters are cool, but for day to
day use, nothing beats a digital meter.

The interesting thing here is that the original post was about replacing
the battery in a VTVM, and the battery is only used for measuring
resistance.

The loading effect doesn't come into play. And it's probably easier to
read ohms on a digital meter than an analog meter.

I would argue that digital meters haven't been as forward looking as they
could. I got one of those Intersil development boards for their famous
DVM IC in 1978. I had big plans for it, never actually done. But I was
going to add a buffer using a mosfet or jfet input op-amp, and feed that
to a cheap meter that had been a signal strength meter in a radio. That
would give the analog movement for tracking peaks and trends, all in one
box. You dn't need to know voltages in that case, just that something has
gone up or down. I hope I would have remembered to put the 1M resistor in
at the tip of the DC meter, just like a VTVM. I can't remember what else
I'd planned.

Yes, one of my DMMs has an "analog" display, but it's sluggish, works off
the DMM rather than directly off the input voltage. I know at one point
there was at least one DMM that had a small analog meter built in for
reading those peaks, a really good solution.

There is no reason we couldn't see multiple test leads (or a lead with a
switch to bypass that 1meg resistor in the tip) in DMMs, it just simply
didn't happen. When I used my HP 410B a lot, I'd always be tangling (and
untangling) the leads, since it had one for AC, one for DC, and one for
ohms. So some consideration probably was given to that, and likely a
blindspot, "who really needs the isolation resistor in the tip in this day
of digital?".

I wish that cheap DMM actually was useful as a frequency counter, but at
400KHz tops, it can't be. And I wouldn't trust the test leads for even
those upper frequencies.

I wish they didn't use the test leads for the capacitance measuring
section, they have a place on the meter to put the leads in, and the test
leads just cause problems with extra and variable capacitance. I remember
one construction articel in Radio Electronics for a digital capacitance
meter that had an adjustment to compensate for the circuity, so it really
was 0 with no capacitor, useful for those low value capacitors.

I did replace the battery in my RCA VTVM with some circuitry, long
forgotten. I found another RCA VTVM just like it a couple of years ago, a
stray item in a box on a busy street, no sign of other garbage. And DMMs
have become so cheap that last year I got another reasonably fancy DMM for
not much, and a pen DMM, which has it's uses, for ten dollars. We seem to
have passed the point of readily available meters the size of a calculator
It reminds me of that mid-seventies pen DMM from HP, the one with an LED
readout and a switch so you could turn the readout upside down, depending
on how you were viewing it.

The early days of building your own digital meters were much more
cmplicated, endless 7400 series TTL, but it gave flexibility. The same
counter section could be used for a decent frequency counter, a decent
capacitance meter, whatever else you needed to measure. We've lost that,
I can't think immediately of some IC that is readily available and cheap
and provides that counter function, while DMMs have become so cheap that
one can get them for ten dollars, free in some places in the US
apparently. Once we started buying them, we lost the ability to control
how we wanted them.

Michael

 

[William Sommerwerck]

"Michael Black" wrote in message
news:alpine.LNX.2.02.1403211343090.1264@darkstar.example.org...

We seem to have passed the point of readily available meters
the size of a calculator. It reminds me of that mid-seventies pen
DMM from HP...

That was the 970. I carried mine when I worked for Bendix Field Engineering.

I have the complete outfit. Anyone want to purchase it?

Beckman sold a similar product (which you can still find). There's another one
(can't think of the brand) I got for $18. Very, very nice.

 

On Fri, 21 Mar 2014 14:27:08 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:

On Thursday, March 20, 2014 10:44:20 AM UTC-7, William Sommerwerck wrote:
"John Robertson" wrote in message

news:hf6dndiO65hnvrbOnZ2dnUVZ5tudnZ2d@giganews.com...

Actually considering that the battery leaks an alkaline, I can only imagine
that using additional alkaline will only make matters worse.

He's trying to unstick the battery. You want something that will dissolve an
alkalai -- another alkali.

I'm not sure that's relevant: the alkali (usually potassium hydroxide) will have
corroded the aluminum, and you cannot dissolve the corrosion!

There's a few options for removing batteries in this situation, including
lathe-and-boring-tool, but I'd trash the flashlight.

Lye will dissolve the corrosion. Too bad it will dissolve the
flashlight too.
Eric

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com

 

[Baron]

Trevor Wilson scribbled thus:

On 20/03/2014 3:16 PM, captainvideo462009@gmail.com wrote:
I found this circuit somewhere, (I can't remember) to replace the
1.50 volt battery in a VTVM. I have an RCA WV98C Senior Voltohmyst
VTVM that is in perfect condition but doesn't get used very often.
This battery retrofit circuit takes power from the 6.30 volt filament
transformer and is built around an LM317. With a trim pot you set it
for 1.55 volts and you never have to change a battery again. It also
needs to occupy an area no larger than the battery presently does.

As much as I like keeping things original, I'm worried that the
battery is going to leak and rot the inside of the unit. I was going
to build the circuit but it occurred to me that I should probably be
concerned about the current that the LM317 will be dissipating when
the meter is used on the low ohms range. Does anyone have a feel for
the size that an adequate sized heat sink should be in order to
handle this? Thanks, Lenny


**Crazy idea, Lenny:

Move yourself into the 1970s and buy yourself a digital multimeter.
Most of them operate on a 9 Volt battery. Replace the battery every
year and you'll be sweet. Even a US$20.00 meter will give you a vast
improvement in every performance parameter over your ancient POS,
which is likely well outside it's original performance specs.


Like this one:


http://au.mouser.com/ProductDetail/Extech/MN35-WITH-TEMP-PROBE/?qs=sGAEpiMZZMtySgZ4QeaOR6vEN3IEHJ9OqaRLKRQ5wis%3d

One of my meters measures the usual Volts, Amps & Ohms AND light
intensity, sound pressure level, relative humidity and transistor
gain. I recall that it cost me AUS$50.00.

I have a nice collection of analogue meters (I recently acquired a
beautiful AVO 8 Mk7), but I never use them anymore.

Go digital. You will not be sorry.

There is no way that I will give up using my AVO8...

--
Best Regards:
Baron.

 

[John Robertson]

On 03/21/2014 2:27 PM, whit3rd wrote:

On Thursday, March 20, 2014 10:44:20 AM UTC-7, William Sommerwerck wrote:
"John Robertson" wrote in message

news:hf6dndiO65hnvrbOnZ2dnUVZ5tudnZ2d@giganews.com...

Actually considering that the battery leaks an alkaline, I can only imagine
that using additional alkaline will only make matters worse.

He's trying to unstick the battery. You want something that will dissolve an
alkalai -- another alkali.

I'm not sure that's relevant: the alkali (usually potassium hydroxide) will have
corroded the aluminum, and you cannot dissolve the corrosion!

There's a few options for removing batteries in this situation, including
lathe-and-boring-tool, but I'd trash the flashlight.

Yeah, I'd missed the aluminum body bit. Unless this is a collectable
flashlight is should be binned...

John :-#)#

--
(Please post followups or tech inquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

 

[John Robertson]

On 03/21/2014 5:34 AM, dave wrote:

On 03/20/2014 01:30 AM, William Sommerwerck wrote:
wrote in message
news:18841ca2-bf92-4b12-875d-2de16b053998@googlegroups.com...

As much as I like keeping things original, I'm worried that
the battery is going to leak and rot the inside of the unit.

Only if you use a carbon-zinc cell. An alkaline cell should be fine.

Unless it's a Duracell!

https://duckduckgo.com/?t=lm&q=leaky+duracell

My experience is either Duracell or Everready alkaline batteries will
leak. This is based on batteries that were stored in circuit in arcade
games (pinball and video) since 1980 that I subsequently opened,
serviced, serviced and then sold between 2004 and 2011.

Some leaked, most did not. I have lots of pictures...somewhere.

John :-#)#
--
(Please post followups or tech inquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

 

[Trevor Wilson]

On 22/03/2014 6:12 AM, captainvideo462009@gmail.com wrote:

On Thursday, March 20, 2014 12:16:03 AM UTC-4, captainvi...@gmail.com
wrote:
I found this circuit somewhere, (I can't remember) to replace the
1.50 volt battery in a VTVM. I have an RCA WV98C Senior Voltohmyst
VTVM that is in perfect condition but doesn't get used very often.
This battery retrofit circuit takes power from the 6.30 volt
filament transformer and is built around an LM317. With a trim pot
you set it for 1.55 volts and you never have to change a battery
again. It also needs to occupy an area no larger than the battery
presently does.



As much as I like keeping things original, I'm worried that the
battery is going to leak and rot the inside of the unit. I was
going to build the circuit but it occurred to me that I should
probably be concerned about the current that the LM317 will be
dissipating when the meter is used on the low ohms range. Does
anyone have a feel for the size that an adequate sized heat sink
should be in order to handle this? Thanks, Lenny

Besides the things I've already mentioned regarding digital vs.
analog, I've tried checking transistors and diodes with a digital,
and I suppose that you can do it but perhaps it's because I've been
doing this all my life with something like a 260, trying to do this
with a digital drives me nuts.

**Almost every modern digital meter I've ever seen has a diode test
function. It's easy to use and is often conveniently labelled with a
diode symbol.


And Trevor you asked how you insulted
> me. You referred to my meter as a "piece of shit".

**So, not insulted you, so much as called your meter a POS? You have
pretty thin skin, Lenny. I'm pretty certain that if someone referred to
my AVO 8 Mk7 as a POS, I would not be overly concerned. Nor my Fluke 85,
or anything else I own. It's just stuff. If someone called me a liar, or
an idiot, or some other derogatory term, then I would be insulted.


You've never used
> it nor have you ever seen it. So where the hell did that come from?

**I've owned VTVMs of the same vintage (in fact, I think I still have
one stored away somewhere). I still own a FETVOM I built (Heathkit) way
back. I never use it, because it is a POS. It was fine when I built it,
but time has moved on and so have I. It's a collector's (barely) piece
only. Same as my AVO 8, my Simpson 260, my Philips PM2403 (now THERE is
one seriously impressive FETVOM) or my General Radio 1564A (the most
beautifully constructed piece in my collection). They're all way past
being truly useful. But I like having them around. All the batteries
have been removed, of course.

You may have your own opinions but there was no reason for that
comment. Lenny

**Sure there was. You're trying to re-invent the wheel. If you want to
keep your VTVM for sentimental/collector purposes, then it's not an
issue. If you want to use it for day-to-day purposes, there are much
better choices available.


--
Trevor Wilson www.rageaudio.com.au

 

[William Sommerwerck]

For what it's worth...

More than a decade ago I bought four toy "Insecto Bots", new. They came with
three AAA alkaline cells installed, from some totally unknown manufacturer.

http://www.amazon.com/247999-I-B-53-Insecto-Bots/dp/B000TQC9AO

I'd opened them a few times to check, and the cells had not leaked. They still
powered the units, though a bit weakly. The other day I finally discarded
them. There were no signs of leakage.

Yes, cells leak, and yes, Duracell seems more likely to leak than others, and
yes, I've had leaking cells on rare occasions. But why some people here have
had such terrible experiences, I don't know.

If it'll make you feel better... About ten years ago I bought a box of 1000
AAA Polaroid cells on eBay. They're wrapped in pairs, in cellophane. About a
quarter of them have leaked, producing a powdery deposit.