Dear Friends
I need an automatic On/Off timer circuit to drive a water cooler (220V, 5 Amp). The circuit should have two knobs for setting the on time and another for off time. Setting the on time to say 5 minuites and Off time to 10 minutes should keep the cooler on for 5 minutes and shutdown for 10 minutes. The cycle should loop until we dont disconnect both of them from mains.
You can buy a very simple timer just about anywhere that you plug into the wall and then plug the device into it. I'm sure that you can set a 10 minute delay
Mstechca,
Transistors work with a DC supply, don't you think his 220V cooler is AC?
Have you ever made an astable multivibrator oscillator with a cycle time of fifteen minutes? Not enough base current for the transistors from the extremely high value of their base/timing resistors. Too much leakage current in the extremely high value timing capacitors.
Why even bother with a dedicated circuit to control on-off times with 220 volts when at any local store you can pick up a ready made 24 hour on-off timer for about $10. I bought an arlec one for my lead acid battery charger so if I'm working away my wife can safely charge flat batteries. ( you guy's know women can be forgetfull) :wink:
Why even bother with a dedicated circuit to control on-off times with 220 volts when at any local store you can pick up a ready made 24 hour on-off timer for about $10.
Because we like designing and making electronic stuff. Your idea spoils half the fun.
The enjoyment it doesn't spoil is designing and making the variable-frequency high voltage power oscillator it needs to control with pots its on and off times. :lol:
Dear Friends
I need an automatic On/Off timer circuit to drive a water cooler (220V, 5 Amp). The circuit should have two knobs for setting the on time and another for off time. Setting the on time to say 5 minuites and Off time to 10 minutes should keep the cooler on for 5 minutes and shutdown for 10 minutes. The cycle should loop until we dont disconnect both of them from mains.
Many (most?) of the readily-available plug-in timers are electromechanical and have a minimum time resolution of 15 minutes. Not what the OP is after. No doubt there are more elaborate/expensive commercial timers which would fit the bill.
Provided the OP would be content with an OFF period which is a multiple of the ON period then a simple clocked counter should suffice. The clock rate could be varied with a pot, and a multi-way switch could take an output from a selected stage of the counter.