K
Hi
We are doing a project related to PC based speed control of 1/2 HP DC Motor using Type - A chopper (MOSfet). The control circuit we use contains PC Parallel port, Hex buffer (7404), optocoupler (MCT2e) and Nand gate (4093). The output from nand is given to gate of Mosfet which is connected in series with DC Motor. The control logic is good if voltages are checked. The Power circuit is also working well when Mosfet is made On/Off. But when both the circuits are clubbed, the Not gate is blowing up and parallel port pin which is used for control is always high irrespective of value sent to it. The program is written in C language.
The main problem is rised at neutral (ground point). It is blowing up first as and when 220V supply is given to motor. Please give us necessary guidance to the above problem.
Regards
Murali
We are doing a project related to PC based speed control of 1/2 HP DC Motor using Type - A chopper (MOSfet). The control circuit we use contains PC Parallel port, Hex buffer (7404), optocoupler (MCT2e) and Nand gate (4093). The output from nand is given to gate of Mosfet which is connected in series with DC Motor. The control logic is good if voltages are checked. The Power circuit is also working well when Mosfet is made On/Off. But when both the circuits are clubbed, the Not gate is blowing up and parallel port pin which is used for control is always high irrespective of value sent to it. The program is written in C language.
The main problem is rised at neutral (ground point). It is blowing up first as and when 220V supply is given to motor. Please give us necessary guidance to the above problem.
Regards
Murali