This project is a wonderful idea of saving
electric bill when you are using a heavy wattage bulbs. With miniature
components and extreme care you can build a low power lamp dimmer right into the
Without a heat sink, Triac Q1 handles up to a 400-watt lamp.
Instead of a relativity expensive trigger diode, an ordinary neon lamp of the
NE-83 or NE-2 variety can be used. (An NE-83 is treaded for dark operation and
will provide more consistent operation.)
Because the neon does not trip the gate until it conducts, the lamp turns on at
medium brilliance. The lamp can then be backed off to a soft glow. Because the
neon drops out when the applied voltage falls below the neon holding voltage of
approximately 40V the lamp cannot be adjusted as low as it can with a diode
List for Lamp Dimmer
C1, C2 - 0.068.uF,
I1 - NE.83 or NE.2 neon lamp
I2 - External lamp not to exceed 400 watts
Q1 - RCA 40502 Triac
R1 - 50,000.ohm, potentiometer
R2 - 15,000.ohm, 1/2.watt resistor
The only thing you need to adjust is
to tune the potentiometer for proper operation. Always place the neon lamp near
the bulbs so that light can fall on the neon lamp.
Attach the circuit right to the socket of higher wattage bulbs. Save more power
and electric bill.