Help with building a circuit.

Classic Toy Trains Forum
1

Hello to all you eletronic guru’s out there,

I need to build a circuit to replace a 9v battery.
It is currently powering a mini-cam that draws 80mA max. and needs at least 8vdc.

I want to power this cam from the 18vac TMCC track power.

Can someone draw me a simple circuit with all needed components?

Some things I have on hand are; 7812A voltage reg., 1000uF / 25v cap., & a 200v / 1A bridge.
Can I use any of these/

Thank You!

2
  • No advertising. Our forums should not be used as an advertising medium…by individual who want to promote their items for sale or their eBay auctions.
3

The 7812 is a fixed voltage regulator… Check for variable regulator chips like the LM723. rigged with a 9 volt zener as reference it should give you the output you’ll need… For dropping 18 VAC to 9 volt DC your full wave bridge might be overkill. A full wave rectifier will provide DC at 1.4 x the rms AC input. Your raw DC will be around 25 volts and you’ll be dropping 16 volts to get your 9, a waste of power. Also 50 PIV diodes are quite adequate for use with these levels.

4

No advertising. Our forums should not be used as an advertising medium

Did I miss something here? I didn’t see any advertising…

5

I meant that as a hint to Pat that he should delete his ad before expecting help with his circuit.

6

Hey bob,
rule #1

  • Please keep discussions on topic (that is, railroad-related). [and germane to the thread subject I presume]