Help with building a circuit.

[USNRol]

- 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.

 

Hey bob,
rule #1

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

[lionelsoni]

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

[trigtrax]

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

Did I miss something here? I didn't see any advertising... 

 

[trigtrax]

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.

[lionelsoni]

- 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.

 

[eZAK]

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!