On Tue, 5 Nov 2002, Roman Black wrote:

*>Eke Neehr wrote:
*>
*>> No, I don4t trying in lab. I4m testing outdoors
*>> and the relay vibrating when it has to turn off
*>> in the twilight and turn on the lamp!
*>> To place a 1 uF cap between collector
*>> and base don4t works at all !

And just in case it has anything to do with the lamp where you removed the
filter caps you do need a filtered supply for this circuit. For example
by using:

                       D1N4004  Z12V1W  470uF40V
Unfiltered            o-----AK--KA--*---||---GND
                                    |
                                    IN
                             7812      GND---GND
                                    OUT
                                    |
                                    v
                                  your circuit power supply

The zener reduces the voltage to something the 7812 will accept.

Peter

PS: I presume you want to run the lamp on dc because it has some sort of
inverter in it - like it's a lf lamp.

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