Re: Sinking Driver Question

Bob,

I have used this board for a long time.  With an external supply,  the connection are:

Both grounds tie to the GND on the PK2200
The K+ goes to the +lead of the external power supply.

One side of the solenoid goes to +lead (K)
The other side of the solenoid goes to the outputs (HV01).

The chip (2803) is essentially an open collector transistor output.  It grounds the output when ON.  The other leg of the circuit must go to +V.

Make sure you have the grounds tied together, and K correctly hooked up.

Dave



>I'm trying to diagnose a sinking driver circuit on a PK2200 series board which uses two ULN2803A chips.  According to the PK2200 user manual, the output ports are all pulled low (off) on power up.  There is also a sample file which toggles each output channel based on which key on the key pad is pressed. When the program is run, it first turns all ports off via up_setout(). A channel can only have up to a 500 milliamp draw, so I'm using a 12 volt relay which draws only 180 milliamps.  I have the board powered up with the Z-World 24 volt development power supply.  The circuit I'm trying to test with is an external 12 volt DC power supply with the positive lead going one pin of the coil in the 12 volt relay.  The negative lead goes to the "K" pin on the board. The other lead from the coil i
 n the relay goes to an output HV01-HV14 on the board.  With this simple test circuit, all the output pins actuate the relay, when the board is initially powered up or when toggling a port off or on. I've tried 3 different PK2000 boards and they all test the same.  Do the grounds from both power supplies have to be tied together?  What am I doing wrong?
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>Bob
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