I've just finished testing a device that protects the two kits up to
350VDC @ 200MA. nice sparks!

All you need to get is a MOV - I'm using the Panasonic ERZ-V07D220 wich
is rated at 22V and 250A - soldered directly to the lugs on the banana
jacks.

I did not want to clip under 20V, so I can still use the ESR meter to
check the condition of rechargable batteries. If you weren't aware, the
DS (Bob Parker design!) ESR kit K-7214 will also check the ESR of
batteries. I have a brief write up on

http://www.flippers.com/esrkthnt.html#battery

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

On Thu, 09 Mar 2006 01:42:22 GMT, John Robertson wrote:

I've just finished testing a device that protects the two kits up to
350VDC @ 200MA. nice sparks!

All you need to get is a MOV - I'm using the Panasonic ERZ-V07D220 wich
is rated at 22V and 250A - soldered directly to the lugs on the banana
jacks.

Suggested source?

John;

I think there is no reason for it to even tolerate 20 volts. It does
not need any voltage higher than its test signal. Setup to test current
or voltage, doesn't matter.

If you want to test ESR on charged batteries, you can capacitively
isolate it with a large electrolytic.

BTW, what kind of ESR readings should one expect from a given battery ?
Is it like a go/nogo thing, or are you trying to match these batteries
in series or something like that ?

You have piqued my curiousity.

JURB

On 2006-03-08 18:58:29 -0800, said:

John;

I think there is no reason for it to even tolerate 20 volts. It does
not need any voltage higher than its test signal. Setup to test current
or voltage, doesn't matter.

If you want to test ESR on charged batteries, you can capacitively
isolate it with a large electrolytic.

BTW, what kind of ESR readings should one expect from a given battery ?
Is it like a go/nogo thing, or are you trying to match these batteries
in series or something like that ?

You have piqued my curiousity.
JURB

Ah, well, I did provide the link to the battery test on flippers. Not
much info, but it is a guidline for interested folks to expand on.

I wanted to protect the meter from accidental surges. I also want it to
be somewhat idiot proof. So having to remember to put a capacitor in
series with the meter to check a battery is easy to forget...don't ask
how many times I've destroyed a peice of test equipment by touching a
charged capacitor or live circuit (OK, maybe ten times). Bob and I have
had too many (perhaps 20(?) out of 12,000) kits blown up blown up and
more simply damaged.

I got the MOVs (Panasonic ERZ-V07D220) from Digi-Key for $0.34C - about
30 cents US, 20V 250A.

Best to quote messages you respond to as well, so here is the link I spoke of:
http://www.flippers.com/esrkthnt.html#battery

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