Author Topic: Vintage HP 456A current probe/clamp battery problems  (Read 915 times)

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Offline Maviday

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Vintage HP 456A current probe/clamp battery problems
« on: January 21, 2018, 02:03:45 am »
Hey guys. I inherited this wonderful little HP 456A current clamp a while back and I have been trying to find batteries for it with no avail. I have looked at the manual which states that it requires   TWO TR 233,  and   ONE  TR 234  Mallory mercury (stable discharge voltage) batteries. the problem is I don't know anything else about these batteries. I have found that the TR233's are supposedly 4-4.2 Volts, and the TR234 is supposedly 5.33 Volts. Now my plan is to use two or three 18650 or 26650 batteries in series and two separate voltage regulator to supply individual voltages, however I still don't know which of these battery holders takes what. In other words I don't want to assume that the larger battery holder takes two batteries in series and the smaller takes the single battery. Since I have no actual information on the battery sizes it is impossible for me to know for sure. My guess is that the smaller holder takes the single TR234 and the larger takes the two TR233's in series...? Does anybody here have any ideas or advice?

I've attached pictures for reference. I decided to post here as this old conversation is one of the older ones regarding vintage gear per this forum.
Thanks
 

Offline stevebyan

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Re: Vintage HP 456A current probe/clamp battery problems
« Reply #1 on: January 30, 2018, 07:34:57 am »
Quote
My guess is that the smaller holder takes the single TR234 and the larger takes the two TR233's in series...?
If you look at the schematic, the -8 volt rail is the pink wire, the 0 volt common is the violet-white wire, and the +5 volt rail is the red wire. It also shows the -8 volt rail is the one with two batteries.

So, your supposition is correct. The larger battery holder is for two TR233's.
 

Offline Ferisoda

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Re: Vintage HP 456A current probe/clamp battery problems
« Reply #2 on: January 30, 2018, 08:00:16 am »
If I take this information to publish, can I share my knowledge?
 

Offline Maviday

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Re: Vintage HP 456A current probe/clamp battery problems
« Reply #3 on: May 03, 2018, 03:59:31 pm »
Thank you, I hadn't noticed.
 

Offline Maviday

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  • Country: us
Re: Vintage HP 456A current probe/clamp battery problems
« Reply #4 on: May 03, 2018, 04:00:24 pm »
If I take this information to publish, can I share my knowledge?

Okay with me...
 


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