Load Monitor + Switch

[KENCO]

I would like to monitor a 12 vdc supply rail ( Around 2 A full load) . If the 12 volts begins to drop I would like to switch to a dummy load (to keep the switch supply somewhat loaded so the 12v doesn't just jump right back up), and if/when the supply were to go back to a steady 12 V dc switch back to main load.

Now I thought either a voltage comparator + Latch circuit + MOSFET combination or a Hall Effect linear current sensor (ACS712) comparator + Latch + MOSFET combination would work. But I don't know which one would be the better choice.

Anyone do this before? Suggestions?

Thanks,
K.

 

[IanP]

This task can be accomplished using simple shunt voltage regulator concept ..
Here is an example:
**broken link removed**
If you need to 'lose' more power you can connect several transistors in parallel and/or add power resistors in series with collectors ..

Regards,
IanP