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DC motor

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I would be inclined to use a relay with a resitor supplying both the motor and the coil and another resistor in series with the coil so that the relay is just held on. An increase in current would allow the relay to drop out and switch the motor off. You may have to regulate the supply to account for volage variations.
 
oldtimer said:
...use a relay with a resitor supplying both the motor and the coil and another resistor in series with the coil so that the relay is just held on...

hmm very interesting idea..thanks a lot.this should have nothing to do with the "Fast Acting Electronic Circuit Breakers" that i posted isn`t it?

but i just a little bit confused on how the assembly should be?
...use a relay with a resitor supplying both the motor and the coil ...
can i please have the schematic of the assembly so that i might understand it a little bit better..

thanks again
 
The method that the microchip board utilized was to control two relays. If both relays are unenergized, then the motor sees no voltage (both leads of motor shorted to ground). To spin the motor one of the relays is energized which ties the input voltage to one of the motor leads. The other lead is then tied to a current sensing resistor. To spin the motor in the other direction, the opposite relay is energized resulting in current through the motor in the opposite direction and the motor is still tied to ground via the same current sense resistor.

Knowing how much current it takes to raise/lower the window, one could use the voltage across the current sense resistor to set a trip level via analog circuitry in the place of a micro. The trip signal would then force the energized relay to deenergize and stop the motor.

The entire control likely be done by employing a switch, some D-Flip Flops, and a comparator or two...
 
your problem is very simple

See Manz

all u need to do is u put the series register of very smaller value in series with the motor and sense the voltage across it that u give it to the comperator and as soon as the glass window is lifted it will overload the motor increasing the current and voltage across the register increases triggerring your comparater and that high pule is sensed by the amplifier dirving the cut off relay whic was latched. thats all u are done.

another way is to use the limit switch such that while lifting the glass with motor as soon as it reaches the desired value it cuts off the drive relay path and by the same time connecting the reverse relay path.:)
 
your dc motor problem

See Manz

all u need to do is u put the series register of very smaller value in series with the motor and sense the voltage across it that u give it to the comperator and as soon as the glass window is lifted it will overload the motor increasing the current and voltage across the register increases triggerring your comparater and that high pule is sensed by the amplifier dirving the cut off relay whic was latched. thats all u are done.

another way is to use the limit switch such that while lifting the glass with motor as soon as it reaches the desired value it cuts off the drive relay path and by the same time connecting the reverse relay path.:)
 
hello CAN ANY BODY HELP ME ?

I want the circuit diagram for the speed controll of brush less dc motor of about 800 watt using hall effect controll sensor specially to be used for the electric scooter which I want to make since so long can any body help plz
 
does any body have the 38 Khz crystal b coz that exact value of crystal is not available in India I tried almost every possible market I want it for the FM stereo transmission.
 
is there any method of directly simulating the audio in the PC to FM signal and O/P available in the sub miliwatt range at the sound card O/P pin and that when feeded to the F/M transmitter gives stereo signal ? is it possible ?
 
Nigel Goodwin said:
To be honest, I've no idea how it's done - I presume it's by current monitoring?, but I've never even seen what one looks like!.

I fixed my power window motor assy. in my 95 pontiac transport. To cutoff current to the motor, it uses a bi-metallic set of contacts, so a circuit breaker of sorts.

The problem with these (as happened to me), is that they fail in such a way that you cannot get the window up again. So my window was stuck down and I couldn't close it again.
 
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