Guys I appreciate all the help, but I scrapped the IDEA of this working, and hunted, and found a circuit online. I built it but, darn it if it doesn't do the same thing the other one does. (when power is applied the relay trips but does not release.) This time I have a diagram. I built it as it is listed, the only difference is pin 2 in not on a switch it is tied directly to ground. I need this to work using the power as the switch. When power is applied, it triggers the relay for xx seconds, and stops. Resets when power is removed and reapplied. Thanks for the help.
**broken link removed**
Parts
R1 1 1 Meg Pot
R2 1 10 K 1/4 Watt Resistor
C1 1 10uf 25V Electrolytic Capacitor
C2 1 0.01uf Ceramic Disc Capacitor
D1,D2 2 1N914 Diodes
U1 1 555 Timer IC
RELAY 1 9V Relay
That's a pretty big difference. Pin 2 is the trigger. It's active low. It drives a simple RS flip-flop and has priority over Thres.
Not going to work that way.
For what you are trying to do, a 555 is more trouble than it's worth. You need one crummy transistor with a cap and a diode and a couple of resistors on the base.
For what you are trying to do, a 555 is more trouble than it's worth. You need one crummy transistor with a cap and a diode and a couple of resistors on the base.
If you have something like a 12V wall-wart in an appliance timer, you may need to add a resistor across the power supply or NONE of these circuits will work.
If you have something like a 12V wall-wart in an appliance timer, you may need to add a resistor across the power supply or NONE of these circuits will work.
I have a digital wall timer, that is programmable down to the minute, but for my application 60 seconds is too long of a time to be on. (It is for a misting system for a vivarium) So I needed something to cut that time down to anywhere between 5 - 30 seconds.
Thanks. Now believe it or not, I once held a degree in electronics. But that was like 15 years ago. I dug out an old program I had to make circuits. I traced out the original device I posted a photo of. But could not get it to work. I also tried your new schematic and couldn't get it to work either. Dunno maybe I wasn't doing something incorrectly. Here is the Tm15 if anyone wants to look at it. I also download a trial of the old workbench tool, its called multisim now. Coudln't get it to work with these circuits.
I tried it this way, as having all these failed projects is getting pricey.
Need more than "couldn't get it" to help you. And I mean actually build it with wires and all, not on a simulator.
The collector of the final transistor should start at 0V, stay there several seconds, then go up to 12V. The base of the first transistor should be at 1.4V, stay there several seconds, then drop to zero. What are you getting?
Need more than "couldn't get it" to help you. And I mean actually build it with wires and all, not on a simulator.
The collector of the final transistor should start at 0V, stay there several seconds, then go up to 12V. The base of the first transistor should be at 1.4V, stay there several seconds, then drop to zero. What are you getting?
Oh, sorry. I meant that from my previous posts, that all these "physical" builds are failing and its getting expensive to "test" so I went digital so I can see it doing what I want before I invest in building another physical device. Now I bought all the parts from your diagram with some exchanges. Here are the parts I have.
Instead of a 1n2222, I have ecg123a
Instead of 1n4004, I have a sk3017b
all the other components are as given. Sorry If I was vague earlier. Just pulling my hair out for something that should be so simple.
BTW, I did assembly it on a protoboard and it didn't do anything. The relay never tripped. (my multimeter's batteries died so i couldn't take readings.)