ohm meter battery

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

 

[John Robertson]

On 03/19/2014 9:16 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

Hi Lenny,

I can't imagine that the 1.5V battery provided that much current for the
low ohms scale. Otherwise you would burn them out pretty quickly and
leakage would have been a real risk.

Of course you could simply put an ammeter in series with a battery and
see what is drawn, I suspect it will be under 100ma, which means you
won't need much of a heat sink - if any. 500ma would be a small finned
clip on heatsink.

If you have the schematics and remember ohms law you can figure out what
the maximum current draw is for the battery...

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."

 

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

That's correct. I've seen Energizer's and Duracell's leak. In fact I've found that Rayovac's, (the Batteries Plus house brand) are one of the worst. And along with the current crop of crap out there I find it very interesting that it's been many years since I've seen the "leak proof" guarantee printed on the batteries, and have gotten a free flashlight, or "other device" replaced because a battery leaked and ruined it. I suspect that they didn't just "forget" to put that guarantee on there....

I think that I'll try that idea of measuring the current. I suppose that I can use the chassis with an insulator as a heat sink if I determine that the device doesn't have to dissipate that much extra current. Lenny

 

[William Sommerwerck]

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.

 

[Mark Zacharias]

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:lge8ui$qgk$1@dont-email.me...

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.

Sadly, I see corrosion, often severe, with alkaline types as well.

Mark Z.

 

[Adrian C]

On 20/03/2014 10:21, Mark Zacharias wrote:

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:lge8ui$qgk$1@dont-email.me...
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.


Sadly, I see corrosion, often severe, with alkaline types as well.

Years ago, Duracell UK used to have an offer to repair/replace? any item
damaged by their batteries leaking. That's now gone.

Duracells leak, had to throw away a perfectly good camera :-(

--
Adrian C

 

[Allodoxaphobia]

On Thu, 20 Mar 2014 05:21:54 -0500, Mark Zacharias wrote:

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:lge8ui$qgk$1@dont-email.me...
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.

Sadly, I see corrosion, often severe, with alkaline types as well.

Mark Z.

+1

 

[William Sommerwerck]

"Mark Zacharias" wrote in message
news:532ac3b0$0$24923$a8266bb1@newsreader.readnews.com...
"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:lge8ui$qgk$1@dont-email.me...

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.

Sadly, I see corrosion, often severe, with alkaline types as well.

The cell needs to be checked periodically, regardless. The mess caused by
alkaline cells is /rarely/ severe, and can /almost/ always be cleaned up.
That from a lead-acid cell destroys the metal.

We've had the Duracell/Energizer argument before. I've never had trouble with
Energizers. The only alkalines I've ever had leak were Duracells. And those
were all AAs. I've never had Duracell C or D leak.

 

[Pat]

On Thu, 20 Mar 2014 05:17:47 -0700 (PDT), captainvideo462009@gmail.com
wrote:

I suppose that I can use the chassis with an insulator as a heat sink if I
determine that the device doesn't have to dissipate that much extra current. Lenny

Devices don't dissipate current. They dissipate power. In the case
of an ohm meter, measurements are usually short term so when averaged
over a longer period of time, there isn't much power to dissipate via
heat sinks or whatever. I have never heard anyone discuss damage to a
meter caused by high currents when measuring low resistances.

Pat

 

[Cydrome Leader]

Mark Zacharias <mark_zacharias@labolgcbs.net> wrote:

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:lge8ui$qgk$1@dont-email.me...
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.


Sadly, I see corrosion, often severe, with alkaline types as well.

Ditto. The batteries just leaked in my p-touch printer and the gunk
weakened the battery terminals causing some to just break off where they
were bent to act as springs. The cells were energizer, and not the fake
ones from the dollar store.

high drain devices always seem more prone to leakage for some reason.

 

[OldGuy]

"Mark Zacharias" wrote in message
news:532ac3b0$0$24923$a8266bb1@newsreader.readnews.com...
"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:lge8ui$qgk$1@dont-email.me...
The cell needs to be checked periodically, regardless. The mess caused by
alkaline cells is /rarely/ severe, and can /almost/ always be cleaned up.
That from a lead-acid cell destroys the metal.

We've had the Duracell/Energizer argument before. I've never had trouble with
Energizers. The only alkalines I've ever had leak were Duracells. And those
were all AAs. I've never had Duracell C or D leak.

So how to clean up?
Flashlight with alkaline batteries permanetly now glued to aluminum
case. No solvent I have tried works. Even after cleaning the threads
on the cap and screwing the cap back on (batteries seemed dry but still
glued in place) and leaving the flashlight for a week or two, the cap
is glued back on again. A pipe wrench and vice will not turn it.



--- news://freenews.netfront.net/ - complaints: news@netfront.net ---

 

[OldGuy]

On Thursday, March 20, 2014 12:16:03 AM UTC-4, captainvi...@gmail.com wrote:
That's correct. I've seen Energizer's and Duracell's leak. In fact I've found
that Rayovac's, (the Batteries Plus house brand) are one of the worst. And
along with the current crop of crap out there I find it very interesting that
it's been many years since I've seen the "leak proof" guarantee printed on
the batteries, and have gotten a free flashlight, or "other device" replaced
because a battery leaked and ruined it. I suspect that they didn't just
"forget" to put that guarantee on there....

I think that I'll try that idea of measuring the current. I suppose that I
can use the chassis with an insulator as a heat sink if I determine that the
device doesn't have to dissipate that much extra current. Lenny

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.



--- news://freenews.netfront.net/ - complaints: news@netfront.net ---

 

[Michael Black]

On Thu, 20 Mar 2014, Mark Zacharias wrote:

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:lge8ui$qgk$1@dont-email.me...
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.


Sadly, I see corrosion, often severe, with alkaline types as well.

Yes.

I put alkaline in a radio, and left them there, and they leaked too. I
was certainly surprised, since it was precisely the situation I was trying
to avoid.

Michael

 

[William Sommerwerck]

"OldGuy" wrote in message news:lgf64i$2uga$1@adenine.netfront.net...

We've had the Duracell/Energizer argument before. I've never had trouble
with Energizers. The only alkalines I've ever had leak were Duracells.
And those were all AAs. I've never had Duracell C or D leak.

So how to clean up?
Flashlight with alkaline batteries permanetly now glued to aluminum case.
No solvent I have tried works. Even after cleaning the threads on the cap
and screwing the cap back on (batteries seemed dry but still glued in place)
and leaving the flashlight for a week or two, the cap is glued back on
again. A pipe wrench and vice [sic] will not turn it.

That sounds like pathologically bad leakage.

You need something alkaline to dissolve the electrolyte. Household ammonia
usually works. It will also /at least/ discolor the aluminum.

 

[John Robertson]

On 03/20/2014 10:18 AM, William Sommerwerck wrote:

"OldGuy" wrote in message news:lgf64i$2uga$1@adenine.netfront.net...

We've had the Duracell/Energizer argument before. I've never had trouble
with Energizers. The only alkalines I've ever had leak were Duracells.
And those were all AAs. I've never had Duracell C or D leak.

So how to clean up?
Flashlight with alkaline batteries permanetly now glued to aluminum
case. No solvent I have tried works. Even after cleaning the threads
on the cap and screwing the cap back on (batteries seemed dry but
still glued in place) and leaving the flashlight for a week or two,
the cap is glued back on again. A pipe wrench and vice [sic] will not
turn it.

That sounds like pathologically bad leakage.

You need something alkaline to dissolve the electrolyte. Household
ammonia usually works. It will also /at least/ discolor the aluminum.

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

May I suggest that you try a mild ACID - vineger (clear, not malt) works
a treat for neutralizing the alkaline leakage. You may want to dilute
the viniger 50:50 with distilled (or Vancouver, BC, tap) water.

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."

 

[William Sommerwerck]

"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.

 

[William Sommerwerck]

"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. You don't want something that might cause an
acid/base reaction.

Ammonia has always worked for me.

 

[David Platt]

In article <lgf885$1l9$1@dont-email.me>,
William Sommerwerck <grizzledgeezer@comcast.net> wrote:

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.

Alas, I've seen leakage from pretty much every size of alkaline.

One thing I have read, is that alkalines are quite unlikely to leak if
they haven't yet been used... but that discharging them triggers an
electrochemical process that starts the leakage syndrome (swelling
and/or corrosion).

So, if you have a device which is mostly kept around as a standby
(e.g. an emergency flashlight or radio), and isn't actually being
used, then the batteries will probably be OK up through their
published shelf-life date. However, once you use the device and start
drawing the batteries down, it's best to replace them relatively soon
after the first-discharge date (e.g. a year or so).

The devices I've had which have been crudded up or damaged by alkaline
leakage all seem to be of the "light or occasional use" variety, where
the batteries are neither left in an "unused, on the shelf" state,
*or* used up and thus replaced within a couple of months.

 

[John Robertson]

On 03/20/2014 12:34 PM, David Platt wrote:

In article <lgf885$1l9$1@dont-email.me>,
William Sommerwerck <grizzledgeezer@comcast.net> wrote:

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.

Alas, I've seen leakage from pretty much every size of alkaline.

One thing I have read, is that alkalines are quite unlikely to leak if
they haven't yet been used... but that discharging them triggers an
electrochemical process that starts the leakage syndrome (swelling
and/or corrosion).

So, if you have a device which is mostly kept around as a standby
(e.g. an emergency flashlight or radio), and isn't actually being
used, then the batteries will probably be OK up through their
published shelf-life date. However, once you use the device and start
drawing the batteries down, it's best to replace them relatively soon
after the first-discharge date (e.g. a year or so).

The devices I've had which have been crudded up or damaged by alkaline
leakage all seem to be of the "light or occasional use" variety, where
the batteries are neither left in an "unused, on the shelf" state,
*or* used up and thus replaced within a couple of months.

For some history - back around 2004/5 I was selling some New Old Stock
Williams brand pinball and video games that had been sealed in their
factory boxes since 1980. In about 50% of the cases one or more of the
three AA alkaline batteries had leaked enough to damage the battery
holder and in a couple of cases enough to damage the logic board
slightly. These were EverReady or DuraCell batteries (both used by the
same game manufacturers).

Later I had a few more of these games (still sealed) that I sold around
2010 and 2011 - again the batteries either had or had not leaked, and
again the damage was minimal.

In a few cases the 3 batteries still held full charge - 1.56VDC!

I think the reason batteries leak is because of current flow through the
battery, in other words is the battery is sitting on a shelf it is less
likely to leak than if it is a circuit where a tiny bit of current may
flow. If batteries are damp that can lead to self conduction and leakage
too.

I have these old still charged batteries still (somewhere buried in my
shop) in a plastic bag to see how long they will last...

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 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.

--
Trevor Wilson www.rageaudio.com.au