Circuit diagram:
Parts:
R1,R2,R3,R5____470K 1/2W Trimmers Cermet or Carbon (See Notes) R4______________10K 1/4W Resistor R6,R7,R8_________1K 1/4W Resistors R9_____________120R 1/2W Resistor R10,R12.R14______1K 1/2W Resistors R11,R13,R15______1K 1/4W Resistors C1,C2,C3_________1µF 63V Polyester or Electrolytic Capacitors C4______________10µF 25V Electrolytic Capacitor C5_____________100µF 25V Electrolytic Capacitor C6____________1000µF 25V Electrolytic Capacitor D1,D2,D3_____1N4148 75V 150mA Diodes D4_________BZX79C15 15V 500mW Zener Diode D5,D6________1N4002 100V 1A Diodes D7,D8,D9____TIC206M 600V 4A TRIACs (See Notes) Q1____________BC547 45V 100mA NPN Transistor IC1____________4093 Quad 2 input Schmitt NAND Gate IC IC2-IC4_____MOC3020 6-Pin DIP Optoisolators, Triac Driver Output P1_____________SPST Pushbutton SW1____________2 poles 3 ways Rotary, Slide or Toggle Switch SW2____________SPST Toggle Switch 250V 10-15A (See Notes) T1_____________220V Primary, 24V center tapped Secondary 3VA Mains Transformer PL1____________Male Mains Plug SK1,SK2,SK3____Female Mains Sockets
Circuit operation:
This design can be of some interest for those wanting striking light signs, as it can drive up to three 230V lamp strings in three operating modes.
The 15V dc supply is obtained from a nominal 230/24V center tapped ac transformer (T1) and a full wave rectifier (D5 & D6): Zener diode D4 was added to clamp the dc voltage to 15V maximum.
Triacs D7, D8 and D9 are insulated from the control circuitry by means of Optoisolators IC2, IC3 and IC4. IC1A, B and C are wired as monostables and cascaded in order to obtain a rotating sequence when the Mode switch SW1 is set in the Rotate position.
IC1D acts as an astable multivibrator and generates an adjustable flashlight, driving all three lamp strings at the same time when the Mode switch SW1 is set in the Flash position.
The All On operating mode allows all lamps to be on at the same time and can be used either for general illumination or to single out a blown bulb.
Each channel can drive several 230V lamps wired in parallel for each string, provided the maximum current of the Triacs is not exceeded. For example, each channel will be able to drive up to 20 40W bulbs.
The circuit is also well suited for many small bulbs wired in series like the usual Christmas tree lamp strings decorations. As these are very low power devices, a lot of them can be driven by this circuit. The more lamps per string are used, the more satisfactory will be the resulting effect.
Notes:
- A brief push on P1 will be necessary to start the Rotate operation mode.
- The Trimmers R1, R2 and R3 should be adjusted to obtain equal delay times or until a pleasing visual result is obtained when observed from some distance. In any case, the Trimmers can be substituted by three fixed 1/4W resistors of equal value: 100K, 220K or 470K will work fine.
- On Flashing operation mode, adjust R5 until the best effect is obtained.
- The Triac types suggested are not mandatory: you can use more powerful devices with no circuit change.
- SW2 must be a high voltage, high current switch, as it must withstand the total amount of current drawn by all bulbs.
