Driving stall motors and LEDs with half rectified AC current
Hello,
I'm new to the forum. I've been searching it as well as googling for information but I'm not finding anything conclusive.
I have drawn up the attached schematic in iCircuit (Mac) and according to the scope when I switch one of the SPDT the current through the LEDs spikes to more than I'd like and I think the current will blow the LEDs. The voltage also spikes presumably because of the polarity change on the capacitor releases then normalises again over the discharge period (5 t). I did make a prototype circuit and actually blew LEDs.
I need the capacitor because the half-rectified wave is too dirty and makes the motors hum. In all there will be 10 motors attached to this circuit. I'm told that 500mA is enough for 30 of these motors all stalled.
The motor's that are being driven are actually Tortoise switch machines for a model train. Unfortunately I don't know the exact specifications but I've read that the internal resistance is something like 800 ohms.
Adding the resistors in-line with the capacitors to limit current to the LEDs (and to stop a capacitor loop) drops the voltage on the motors which makes them run too slowly. 9VDC is already slower than I wanted to run them.
ALTERNATIVELY... If I were to take two off the shelf 12VDC walwart type power adapters could I achieve a symetrical +12VDC and -12VDC and a common conductor by connecting one of wires a certain way?
Any advice would be appreciated.
Thanks for reading!
Hello,
I'm new to the forum. I've been searching it as well as googling for information but I'm not finding anything conclusive.
I have drawn up the attached schematic in iCircuit (Mac) and according to the scope when I switch one of the SPDT the current through the LEDs spikes to more than I'd like and I think the current will blow the LEDs. The voltage also spikes presumably because of the polarity change on the capacitor releases then normalises again over the discharge period (5 t). I did make a prototype circuit and actually blew LEDs.
I need the capacitor because the half-rectified wave is too dirty and makes the motors hum. In all there will be 10 motors attached to this circuit. I'm told that 500mA is enough for 30 of these motors all stalled.
The motor's that are being driven are actually Tortoise switch machines for a model train. Unfortunately I don't know the exact specifications but I've read that the internal resistance is something like 800 ohms.
Adding the resistors in-line with the capacitors to limit current to the LEDs (and to stop a capacitor loop) drops the voltage on the motors which makes them run too slowly. 9VDC is already slower than I wanted to run them.
ALTERNATIVELY... If I were to take two off the shelf 12VDC walwart type power adapters could I achieve a symetrical +12VDC and -12VDC and a common conductor by connecting one of wires a certain way?
Any advice would be appreciated.
Thanks for reading!
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