I found this little toy at the local Menard's home building supply center today for $3.99. They are Intermatic 300 series 7 day 20 event self powered and self contained digital timers.
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Whats interesting is they have very basic power and control circuits that are very easy to modify for different input and output voltages and applications. The power circuit is basically a capacitive coupled line driven to 24 volt DC source that drives a small relay for the actual line voltage output switching.
The actual digital timer is only a three wire system that runs off of a 1.2 volt button cell battery.
This makes the timer itself basically independent of its power source and output systems. All it uses is a simple transistor to switch on the relay with the 1.2 volt signal from the actual timer circuit.
Because the case is split into two pieces and the internal circuitry is split into two independent circuit boards, timer and power, these are probably the simplest and cheapest off the shelf multi function digital timers you will find that can easily be reverse engineered to work on almost any type of timing applications plus still retain the full front face and appearance!
I am planning to modify them work with 20 amp heavy duty relays instead of the cheap 5 amp one they have in them now. They have plenty of internal room and circuit board space for fitting much higher capacity relays or what ever else in them as well!
Or you can just take them apart and stick the face on something else and modify the control circuits to work with your particular power and output needs! The face itself actually has three points that are made for screws to hold them in place so they are about as simple and easy as a person could ask for when modifying an off the shelf item!
**broken link removed**
Whats interesting is they have very basic power and control circuits that are very easy to modify for different input and output voltages and applications. The power circuit is basically a capacitive coupled line driven to 24 volt DC source that drives a small relay for the actual line voltage output switching.
The actual digital timer is only a three wire system that runs off of a 1.2 volt button cell battery.
This makes the timer itself basically independent of its power source and output systems. All it uses is a simple transistor to switch on the relay with the 1.2 volt signal from the actual timer circuit.
Because the case is split into two pieces and the internal circuitry is split into two independent circuit boards, timer and power, these are probably the simplest and cheapest off the shelf multi function digital timers you will find that can easily be reverse engineered to work on almost any type of timing applications plus still retain the full front face and appearance!
I am planning to modify them work with 20 amp heavy duty relays instead of the cheap 5 amp one they have in them now. They have plenty of internal room and circuit board space for fitting much higher capacity relays or what ever else in them as well!
Or you can just take them apart and stick the face on something else and modify the control circuits to work with your particular power and output needs! The face itself actually has three points that are made for screws to hold them in place so they are about as simple and easy as a person could ask for when modifying an off the shelf item!
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