Dear All,
I have a single board controller prototype with a power supply problem (circuit diagram attached).
Question: Can a circuit be created to provide a 5VDC microprocessor with sufficient power, when the single 12VDC power supply is also driving other 12VDC components?
I have an externally supplied 12VDC, 2A power supply normally responsible for energizing one 5VDC item through an LM7805CT voltage regulator, but occasionally required to power four items simultaneously.
The items are:
o One 5VDC Microchip PIC16F876 microprocessor
o Two, 12VDC SPDT relays with 12VDC, 200 milliwatt coils
o One external 12VDC, 3 watt coil load, connected, long-distance to the relays via a 25 foot long, 24 gauge wire pair.
Normally the microprocessor operates perfectly; however, when the 12VDC relays are actuated (occasional 100 millisecond pulse), to send 12VDC to the distantly-located 3 watt load, the microprocessor’s 5VDC drops too low and it stops working mid-program.
I think my 12VDC, 2A external power supply is sufficient to power all components simultaneously; however, when current starts flowing into the 25foot wire pair, it momentarily starves the LM7805CT voltage regulator which stops the microprocessor.
Case 1: When the relays are actuated, with the distant load connected, the PIC microprocessor is denied sufficient power and it freezes.
Case 2: When the relays are actuated, with the distant load disconnected, the relays and the SBC PIC continue to operate okay.
I have a single board controller prototype with a power supply problem (circuit diagram attached).
Question: Can a circuit be created to provide a 5VDC microprocessor with sufficient power, when the single 12VDC power supply is also driving other 12VDC components?
I have an externally supplied 12VDC, 2A power supply normally responsible for energizing one 5VDC item through an LM7805CT voltage regulator, but occasionally required to power four items simultaneously.
The items are:
o One 5VDC Microchip PIC16F876 microprocessor
o Two, 12VDC SPDT relays with 12VDC, 200 milliwatt coils
o One external 12VDC, 3 watt coil load, connected, long-distance to the relays via a 25 foot long, 24 gauge wire pair.
Normally the microprocessor operates perfectly; however, when the 12VDC relays are actuated (occasional 100 millisecond pulse), to send 12VDC to the distantly-located 3 watt load, the microprocessor’s 5VDC drops too low and it stops working mid-program.
I think my 12VDC, 2A external power supply is sufficient to power all components simultaneously; however, when current starts flowing into the 25foot wire pair, it momentarily starves the LM7805CT voltage regulator which stops the microprocessor.
Case 1: When the relays are actuated, with the distant load connected, the PIC microprocessor is denied sufficient power and it freezes.
Case 2: When the relays are actuated, with the distant load disconnected, the relays and the SBC PIC continue to operate okay.
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