Lamp Pulser

Published:2013/7/23 21:03:00 Author:muriel | Keyword: Lamp Pulser | From:SeekIC

Parts:R1,R2 4K7 1/4W ResistorsR3 22K 1/4W ResistorR4 2M2 1/4W Resistor (See Notes)R5 10K 1/4W ResistorR6 47R 1/4W Resistor (See Notes)C1 1µF 63V Polyester CapacitorD1 5mm. Red LED (See Notes)IC1 LM358 Low Power Dual Op-ampQ1 BC337 45V 800mA NPN Transistor Circuit operation:This circuit operates a LED in pulsing mode, i.e. the LED goes from off state, lights up gradually, then dims gradually, etc.This operation mode is obtained by a triangular wave generator formed by two op-amps contained in a very cheap 8 pin DIL case IC. Q1 ensures current buffering, in order to obtain a better load drive.R4 & C1 are the timing components: using the values shown in the parts list, the total period is about 4 seconds. Notes:The most satisfying results are obtained adopting for R4 a value ranging from 220K to 4M7.Adopting for R4 a value below 220K, the pulsing effect will be indistinguishable from a normal blinking effect.The LED can be any type and color.You can use a filament lamp instead, provided its features are comprised in the range 3.2 to 6V, 200mA max.Using a lamp as a load, R6 must be omitted.Voltage supply range can be 4 to 6V: 4.5V is the best compromise.Don't supply the circuit with voltages exceeding 6V: it will work less good and Q1 could be damaged when a lamp was used as the load.At 6V supply, increase R6 value to 100 Ohm.



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