I have a radio control receiver. The receiver circuit controls the direction of a motor, but the wiring does not make sense to me.
There are 2 wires to the motor. Each wire is controlled by a pair or transistors : 8550ss and 8050ss. I figure that these are controlled by the IC and depending on the signal received, switch the current in the required direction.
Here's the confusion :
( example of 1 wire, but all seem to be wired the same )
Ground is connected to 8050 Emitter.
Motor ( wire 1 ) to the Base.
Collector is connected via circuitry to the IC.
My (limited) understanding is that the base should be connected to the IC, and Collector / Emitter to the Ground / motor path ?
but what I have here does work - I just don't understand why.
If you reasearch H-drive circuits you will see that when you need to be able to control direction as well as speed for a motor, 4 main transistors are required, 2 for each motor drive.
What I am wanting to do is 'pimp up' the car to a larger motor and 9V DC battery.
However, the board and the output will not handle more than 6V ( I found out why at the expense of another board ).
So my thinking is to drop the voltage going to the board from 9V to 5V, keeping all the components on the receiver board, and the h-bridge, from failing.
Then, using the parts that I have in my box, add the following :
Using this, a signal on either A or B would power the motor in the required direction.
Consider adding a diode from positive to negative right in the same connections on you motor. This will make the voltage flow in one direction and would prevent the electronics from getting damaged when the motor if off but still spining.
mixania:
Consider adding a diode from positive to negative right in the same connections on you motor. This will make the voltage flow in one direction and would prevent the electronics from getting damaged when the motor if off but still spining.
Am moving back to this project to start clearing my hobby workbench.
I understand the need for the diode, but how can it possibly be added to this circuit ? The 'Signal A' / 'Signal B' options allow for the motor direction to be controlled by changing the polarity ( correct term ? ) of the power going to the motor. So the positive supply to the motor could be on either pin ?
The only possibility that I can imagine, is if the diode is placed at the source of the 9V, but that would be before the 2N3904 transistor and the C106 Thyristor, thereby placing them at risk ?
Use a full-wave bridge.
Put either of the FWB's AC terminals to either of the motor terminals.
Connect the FWB positive terminal to +Vsupply.
Connect the FWB negative terminal to Gnd.
if I think I understand your idea, it is using a conventional bridge rectifier, that usually converts AC to DC, in reverse operation, with the motor connected to the conventional AC input, and 9VDC supply on the conventional DC output side ?
I assume then that I would require 2 rectifiers ( 1 for each motor direction ) and that the diodes would protect the battery pack from any surges ?
DaveO:
if I think I understand your idea, it is using a conventional bridge rectifier, that usually converts AC to DC, in reverse operation, with the motor connected to the conventional AC input, and 9VDC supply on the conventional DC output side ?
I think you've got it.
DaveO:
I assume then that I would require 2 rectifiers ( 1 for each motor direction ) and that the diodes would protect the battery pack from any surges ?
No, just the one FWB. Mostly it'll keep the semiconductors from getting whacked.
C109 - that's an SCR. Are you suing using that as a place keeper? Or what did you intend there?
You have no base resistors.
Is the drawing intentionally short on details as a preliminary sketch-up?
My thought was to have the transistor control the ground / low side of the motor, and the C106 gate, once activated, the high side. Once power is removed from the transistor, current will stop flowing and the C106 would close ( not certain of the correct term ).
There is no base resistor as the 3V would be supplied by the board that this is being 'added' on to. I really like your idea of using the FWB, but I was hoping not to have to order more components and use what I have in my stash.
