I have a commercially purchased SCR controller which I use to control a 220v element. The controller has performed exceedingly well and is capable of an output of 4 000W, my current element is only 2 700W. My only issue it that I would like the output to be controllable to +-5W, to achieve this takes significant back an forth adjustments with the potentiometer to dial in the required wattage.
I though a solution would be to install additional 2W resistors in some form of parallel / series configuration with a selector switch or switches that would allow me to have finer resolution in the ranges that I work. I don't know how to go about this.
This morning I checked the two spare controllers I have. The output power is driven by a pot with markings 500k pot rated for 2W. Oddly enough both are identically marked but in both cases the the pots measure 4.7k when isolated from the circuit.
When sweeping the knob on the pots when connected to the multi-meter I seem to have found the problem. The pots are connect such that fully CCW or eight o clock the reading is 4.6k, at half past three it is 4.0k it then plummets to zero from half past three to 5 o clock. Both are the same and I hope my multimeter is not playing up. Is there something about pots in SCR circuits that I fail to understand?
Pot data sheet WTH118-1A series potentiometer for resistance input SSR or voltage regulator (finglai.com) The pot data sheet does not indicate that a 500K is available.
So apart from the fact that the pots appear to be faulty. Could anyone make any recommendations that will allow me to alter the resolution of the power output.
thanks
I though a solution would be to install additional 2W resistors in some form of parallel / series configuration with a selector switch or switches that would allow me to have finer resolution in the ranges that I work. I don't know how to go about this.
This morning I checked the two spare controllers I have. The output power is driven by a pot with markings 500k pot rated for 2W. Oddly enough both are identically marked but in both cases the the pots measure 4.7k when isolated from the circuit.
When sweeping the knob on the pots when connected to the multi-meter I seem to have found the problem. The pots are connect such that fully CCW or eight o clock the reading is 4.6k, at half past three it is 4.0k it then plummets to zero from half past three to 5 o clock. Both are the same and I hope my multimeter is not playing up. Is there something about pots in SCR circuits that I fail to understand?
Pot data sheet WTH118-1A series potentiometer for resistance input SSR or voltage regulator (finglai.com) The pot data sheet does not indicate that a 500K is available.
So apart from the fact that the pots appear to be faulty. Could anyone make any recommendations that will allow me to alter the resolution of the power output.
thanks
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