Circuit_Two-wire_Lamp

Manu

Home

Two-wire Lamp Flasher

Circuit Description :

This circuit has been designed to provide that continuous light lamps already wired into a circuit, become flashing. Simply insert the circuit between existing lamp and negative supply.
Especially suited for car or panel pilot lights, this device can drive lamps up to 10W.

Parts:
R1 =6K8 1/4W Resistor
R2=270K 1/4W Resistor
R3=22K 1/4W Resistor
C1=220?F 25V Electrolytic Capacitor C2=10?F 25V Electrolytic Capacitor D1=1N4002 100V 1A Diode
Q1=BC557 45V 100mA PNP Transistor Q2=BD139 80V 1.5A NPN Transistor LP1=Existing filament Lamp: any type in the range 3-24V 10W max.
SW1=Existing On-Off switch
B1=Existing V DC source: any type in the range 3-24V
suited to the lamp adopted

Schmatics diagram

Notes:

Break lamp(s) to negative supply connection(s), then insert the circuit between existing lamp(s) connection(s) and negative supply (respecting polarities!).
C1 value can be varied from 100 to 1000?F or higher, in order to change flashing frequency.
Although rather oversized, this circuit can also drive any LED, providing a suitable resistor is fitted in series with the light emitting device.
The resistor should be in the range 47R to 2K2, depending on supply voltage.