MK 111 again - relay change question

Kits Mini Kits Range
1

Hello and thanks for hosting a forum for these minikits, it’s really handy for amateurs & beginners !

Anyway here’s my question. The 12V voltage required for the relay is quite impractical for my usage. Available 12V accumulators are too heavy, the GP23 batteries seem to be too weak to properly trigger the relay and having a lot of 1.5V batteries is almost as bulky as the accumulator :frowning:

So here are my 3 questions please :

  1. When using a GP23A 12V battery, the relay keeps switching on and off all the time if I set both resistors to minimum (as if both delays were around 0.5s). Then if I adjust the pause resistor to halfway, the relay stays stuck at the same position forever (i waited 10 minutes) and the LED is on all the time. I have to switch the power off to reset the relay. Quite strange since I triple checked and all the components are soldered correctly. What could cause such a behaviour ? too weak battery ?

  2. What kind of portable power source would you advise after 1), accumulator or set of 6x1.5 or 2x6V batteries or anything else ?

  3. If I try to power the kit with a regular 9V battery, I don’t experience the issues above and everything works fine, even if I set the pause resistor to max, it perfectly and regularily triggers every 70 seconds as designed. However, the relay is not triggered since 9V is not enough for it. Important : the switching circuit is very low voltage & current. I tried to simply connect it to the pins of the LED and it triggers perfectly with the 9V battery and without relay at all.

Is it possible to replace this relay with one that would trigger at 9V or 6V and still keep all other components as is ? If I have to look for such a relay, what specs other than the voltage should it meet ? Any suggestions/reference/hint for such a component please ?

Thanks a lot for your time & insight!

2

GP23A is a remote control battery for intermittend use.
Not suited for other application.

You need a proper 12VDC source capable of delivering at least 50mA continuously.
Unit will not work reliable on 9VDC.

3

Ok for the battery thanks.

Why would it not work to replace the VR15M121C relay (12V) by the exactly same VR15M061C but operated by 6V ?

They have the exact same specs except the internal resistance and coil voltage …

I surely don’t understand something, please explain to me briefly at least.

Also, I would like to replace the default red LED by another one, apart from the 3mm size there are no additional specs on the package, is it a simple standard 3mm LED ? (I think so, just to be sure …)

Thanks

4

6V relay fed with 9 or 12V will destroy the relay eventually.
Led can be changed without a problem.

5

Great for the LED. As for the relay, I thought to feed the whole thing with 6V, as when now if I feed it with 9V everything works except the relay coil, I think everything will keep working at 6V, why not ?

Besides, the minikit says it can be fed 12-15V so looks like 15V is not destroying a 12V relay ? Im just trying to understand :slight_smile:

6

15V on a 12V relay is +25%, 9V on a 6V relay is +50%
Circuit has not been tested on 6V. Please experiment.

7

Ok thanks for your support :slight_smile:
I’ll post my findings, can be useful for others