Hi guys, sorry for the noob question.
I am trying to build a delay timer, that switches off a fan 15 mins after the light is switched off, with mostly only available parts.
I have:
220 uF, 110 uF capacitors
6 BJT's (9013)
a relay (5VDC coil)
Various resistors.
I'm gonna run it from 4x1.5 batteries for now.
Right now I built the model with a circuit simulator applet at Falstad http://www.falstad.com/circuit/
Please see the attachment, I'm setting the first resistor to be 1Mohm, but I only get 19secs before it switches the relay and that's already a ridiculously high value.
Any tips on how to make the delay longer, to reach 15 mins?
Does the value on the other two resistors matter? I only use them to pull up the BJT bases but could playing with their values affect the delay time?
Thanks a bunch, sorry for the newbie question.
I am trying to build a delay timer, that switches off a fan 15 mins after the light is switched off, with mostly only available parts.
I have:
220 uF, 110 uF capacitors
6 BJT's (9013)
a relay (5VDC coil)
Various resistors.
I'm gonna run it from 4x1.5 batteries for now.
Right now I built the model with a circuit simulator applet at Falstad http://www.falstad.com/circuit/
Please see the attachment, I'm setting the first resistor to be 1Mohm, but I only get 19secs before it switches the relay and that's already a ridiculously high value.
Any tips on how to make the delay longer, to reach 15 mins?
Does the value on the other two resistors matter? I only use them to pull up the BJT bases but could playing with their values affect the delay time?
Thanks a bunch, sorry for the newbie question.
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