240v UVC lamp

[GadgetBoy]

So, bought this thing on eBay, seller didn't mention that it was a 240v bulb... Is there an easy way to change the components on this to make it function on 120v?

[TheMG]

Add a capacitor and use the bridge rectifier as a voltage doubler like what was commonly done in computer power supplies with the voltage selector switch.

 

[GadgetBoy]

I think I know what you mean. Add the cap in the "middle" of the rectifier?

[james_s]

Reconfigure the input as a voltage doubler.

The usual configuration is a full wave doubler, it looks like a bridge rectifier except it uses two diodes and two capacitors instead of four diodes.

https://electricalacademia.com/electronics/half-wave-full-wave-voltage-doubler-working-circuit-diagram/

You might also find that it works fine on 120V perhaps at slightly lower than rated brightness. I have some 240V CFLs from England and I was surprised to find they work fine on 120V although I don't know if that would be detrimental to their lifespan.

[GadgetBoy]

It does not function on 120 (it's a quartz UVC lamp), so I'm hoping to get it working.

From what everyone is saying, it looks like my original plan of putting a single stage WC on the mains input should do the trick.

[GadgetBoy]

Found this, which confirms the mental idea I was forming of how to set this up.

[james_s]

That will work, but it is more complicated than it needs to be. Notice that each of those capacitors is actually in parallel with D3 and D4, so those two diodes can be eliminated and replaced with the capacitors.

[GadgetBoy]

Last question, do the caps have to be polarized as indicated in the diagram?

[Gyro]

No, they don't have to be, it's just a matter of getting a large capacitance in a small space (electrolytics). The polarities shown are the ones you must use if they are polarized, to avoid reverse biasing them.