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I have had a bat in the bedroom on two occasions in my house. Quite frightening when you wake up in the middle of the night to discover a bat flying around the room! Actually the lovely wife Morticia was awakened first, and woke me up. I think she attracts them.Hee, hee. You have bats in your bedroom? Then do you live in a cave or in a tree?
Thanks for the reply . I am worried that keeping the relay coil energized for a long period might over tax a small transistor .I would think that the BD140 is not necessary. T2 has to switch 44mA which most small transistors can manage. Look up the data sheets. I do nor remember all the numbers so I go for a 2N2222 which I can remember.
Put the relay in T2 collector circuit. If you switch T2 fully on and off you will not need a heat sink.
R1 could be about 1k. This would limit T2 base current to about 10mA
Thanks for the reply . I was not aware this was any kind of timing circuit it stated toggle switch . I don't want anykind of timed switch just on and off when required . Have I got the wrong 555 circuit ? I don't want to switch the full 4 amp current from a 12 meter line . The 12 meter switch line should give clues to the fact it's outside and I want it switched " from " the bedroom . I will try it with just the 555 that may cut out some issues . I said I was new to electronics like I started last week . So cut me some slack please .Hee, hee. You have bats in your bedroom? Then do you live in a cave or in a tree?
With pin 2, pin 6 and the capacitor of the 555 connected together then you have made an oscillator, not a timer.
Why do you use two transistors for the relay coil when the datasheet of a 555 says it can produce up to 200mA?
The datasheet for a 555 timer shows that with your 100k resistor and 1uF timing capacitor then the timing duration will be only 0.1 second, not for a long duration.
Make it like this:
You said that the relay contacts are NC which is Normally Closed. Then they conduct when the circuit and pushbutton are not used. You also said that you want the relay contacts to stay open for long periods. Then the pushbutton activates the 555 timer circuit which opens the relay contacts for a long timing period.Thanks for the reply . I was not aware this was any kind of timing circuit it stated toggle switch . I don't want anykind of timed switch just on and off when required . Have I got the wrong 555 circuit ? I don't want to switch the full 4 amp current from a 12 meter line . The 12 meter switch line should give clues to the fact it's outside and I want it switched " from " the bedroom . I will try it with just the 555 that may cut out some issues . I said I was new to electronics like I started last week . So cut me some slack please .
There is no church with a steeple where I live but I frequently see bats flying at dusk in a nearby park. Maybe they live in a hollow tree trunk.I have been told that I have bats in my belfry.