This is the jumper I'm referring to.I see that you have left out the jumper that I added between the -Ve of the bridge rectifier and the capacitor -Ve.
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This is the jumper I'm referring to.I see that you have left out the jumper that I added between the -Ve of the bridge rectifier and the capacitor -Ve.
I can find no problem in the layout.I built another unit today. The problem I am having now is the timing works correctly but after the time delay the motor starts again in the same direction. Below is a layout for the latest prototype.
Your Q4 is defective. Therefore it cannot trigger the 555 to stop the motor. CD4013 is responsible for changing direction of motor rotation and not for stopping the motor.After 3-4 reversal ops the switches again have no effect on the ckt. At this point I took voltage measurements. 0v @ both pin 4 and 6 of 4013, 3.5v @ Q4 gate.
One only measures component resistance with power off. With power on, you risk damage the component, getting incorrect value or damage the meter. The 370Ω coil resistance of the relay is ok. They draw only 40mA at 15V so no problem there for the 2N7000.The cathode of D3 on relay one is attached to pin #3 of 555, the anode to -vc. The cathode of D4 on relay 2 is attached to +vcc, the anode to drain of Q1. The resistance of the relay coil is 360 ohms. I measured the relay coils both w/ and wo power. Power on relay 1 = 27ohms, r2 = open.
Power off r1 & r2 = 370 ohms. I also measured voltages to the following:
4013 p14=14.7v, p1=14.7v,q1 gate=3.7v, p4=.03, p6=0.0v.
That could be part of the reasons. One reason could be the surge or voltage peak from switching off the motor getting back into the low voltage circuit. This can be eased by fitting a resistor+capacitor snubber across the relay contact.Yes, by cathode I am referring to the banded end of the diode. As to the 2N7000 I purchased them through an EBay store in Asia. I won't do that again. I purchased new units from Allied Electronics, a large US distributor.
I will wait for them before assembling another board.