230V DIMMER
Original source:
Velleman kit (K5001).
Description:
A reliable and efficient all-around performer. I bought the kit because it didn't cost me much more than the components were worth and I also got a nice professional-made PCB inside.
As you can see, this is a tried-and-true diac & triac combination that offers both simplicity and high performance. With a load up to 3.5A, the power rating is 750W at 230V. A heat sink on the triac is a must!
Note: for 110V operation, add a 220k resistor in parallel with the 470k pot. No other modification is necessary. But since the maximum allowed current is still 3.5A, the highest possible power output will drop to 380W.
Problems:
Insulate all mains voltage connections and mount the circuit in a sturdy plastic box with enough room inside for the air to circle freely.
Possible uses:
When I bought a mains voltage powered soldering iron (a Weller 25W), I was appaled at the rate at which the tip had to be replaced. Obviously, the soldering iron was badly overheating. I asked around a bit and quickly learned that this was not just a problem of my beautiful little Weller. Virtually all mains powered irons suffer from the same problem.
The only solution is to build a dimmer. This one has served me very well. Now, I can easily control the temperature of the tip and select maximum power only when I really need it. Other applications are light dimming (for incandescent lamps only!) or AC motor control.
