Picaxe 28 pin project board

[DaveBl]

Hi people, I have a problem with the picaxe 28 pin project board.

I am attempting to control 24v dc relays via the darlington chip. This I have done
many times with 40X project board with external driver chips. However, When I connect
the board using a single 4.7v supply, all is well. I can talk to the 28X1 etc. As soon as I
common the 0V from the 24V relay supply with the 4.7V supply 0v I lose communication
with the chip and the voltage across the chip supply is reduced to 3.6V....... strange.
If I then connect the +24V to the V2 supply and change the jumper settings as per the manual the chip blows up due the voltage raising to +13 odd volts...... stranger.

So can anyone tell me where I am going wrong, possibly supply an absolutely definitive
diagram for this application PLEASE. In other applications using elays it has only been neccesary to common the 0 volts and off it goes!

Thank you all

Dave Black

 

[eclectic]

@Dave

I've just tried a simplified version, using an AXE020
Axe 28X1 and ULN2803 in circuit.

First.
2x AA cells / jumper link in left-hand position.
Voltage on both sides of the board = 3.04v

Second.
Completely remove the jumper-link.
4 x NiMh connected as shown in
AXE020 manual page 1, bottom diagram

Left-side side board voltages = 3.04v
All Right-side side voltages = 5.10v

What else do you have connected?
How is it connected?

e

Addedit
Could you do another set of tests, but remove all chips first?