13-02-2014, 12:19 AM
(This post was last modified: 13-02-2014, 12:20 AM by AlanBeckett.)
To continue .....
I couldn't immediately remember why I'd put it to one side, apart from vague memories of needing obsolete Batteries - old age I expect.
I assumed that it required a couple of the usual AVOMinor-type batteries but they wouldn't fit so I did a search. It slowly dawned on me that it needs a couple of these - http://www.smallbattery.company.org.uk/s...EREADY,413
Make sure you're sitting down before you access the Link and look at the Price.
Just to make sure I connected my trusty Farnell PSUs - plural - in place of the Batteries and it did what it said on the Card. It's difficult to see what's going on in there but it's possible to see a 175k Resistor. Sure enough putting an AVO 8 across the Spikes gives 340 MicroAmps - near enough.
Just as a check I put a series of Resistors plus an R-Box across the Spikes with the following results:-
39k = 80%
120k = 60%
1M = 22%
2M = Edge of 'Dry'
3M9 = 18%
In the usual manner of Constant Voltage Resistance scales it's compressed at the top.
So, what to do about the Batteries?
After a bit of Research and Drawing it seems possible to make a couple using Lithium Button Cells - CR1225s - and a suitable Enclosure.
Something like this:-
Plastic probably although there really isn't much material to spare in the 15mm direction.
Suggestions?
Alan
I couldn't immediately remember why I'd put it to one side, apart from vague memories of needing obsolete Batteries - old age I expect.
I assumed that it required a couple of the usual AVOMinor-type batteries but they wouldn't fit so I did a search. It slowly dawned on me that it needs a couple of these - http://www.smallbattery.company.org.uk/s...EREADY,413
Make sure you're sitting down before you access the Link and look at the Price.
Just to make sure I connected my trusty Farnell PSUs - plural - in place of the Batteries and it did what it said on the Card. It's difficult to see what's going on in there but it's possible to see a 175k Resistor. Sure enough putting an AVO 8 across the Spikes gives 340 MicroAmps - near enough.
Just as a check I put a series of Resistors plus an R-Box across the Spikes with the following results:-
39k = 80%
120k = 60%
1M = 22%
2M = Edge of 'Dry'
3M9 = 18%
In the usual manner of Constant Voltage Resistance scales it's compressed at the top.
So, what to do about the Batteries?
After a bit of Research and Drawing it seems possible to make a couple using Lithium Button Cells - CR1225s - and a suitable Enclosure.
Something like this:-
Plastic probably although there really isn't much material to spare in the 15mm direction.
Suggestions?
Alan
