Relay Interfacing

[rob.beckett]

Hello,

Ive made up a variboard with 7 relays on it. I'm planning on using the relay interface circuit as found in the manuals.
The relays are 5v but wanted them on a separate battery to the PIC, so there is just an input from the pic with the 0v common.

When I plug in my battery ( with the picaxe board not connected) one of the relays picks. Only one, the rest behave how i'd expect. ie not pick until the pic outputs to turn on the thyristor.
This is really strange, I've checked the soldering over and over, and then restarted everything. but still one relay picks.
Just wondering if anyone else has had this problem when dealing with several relays next to one another?
Its like a voltage is being induced from somewhere.
Ive got 5v rails and 0v rails and am sure that there are no interconnections.
Does anyone think that it could be the thyristor failing?

Thanks in advance for any help!!

Rob

 

[westaust55]

Welcome to the PICAXE forum.

Do you have a pull-down resistor on the signal line to the "transistor"?

You mention a thyristor whereas the PICAXE MAnual 3 page 7 disucces Darlington trnasistors and Power Mosfets.

Please upload a schematic diagram of your circuit.

Another point - do you have the 0V of both supplies conencted together?

 

[Andrew Cowan]

If you don't have a schematic, a good photo could be of some help to us.

 

[MPep]

There may also be a problem within your code. Please post this so we may glance over it. Thanks.

 

[rob.beckett]

Hi,

Problem sorted. I was using transistors, not thyristors. One of them was failing, allowing current to flow through the device when not even triggered. I bought a new transistor, and jobs a good un!

I have incorporated the pull down resistors - I should have done that before!

thanks for your help! ......

back to soldering

 

[rob.beckett]

Hello, (again!)

Sorry to be a a pain, i read a post on here about connecting 2 picaxes together to communicate serially.I've had a search, but nothing came up.

Could someone point me in the right direction?

Thanks
Rob

 

[MPep]

Simply put: use SEROUT and SERIN. Either use a handshaking line from the transmitter to 'say' to the receiver "hey, wake up I need to tell you something", use use a qualifier in the send string. Only (potential) problem with this is that some PICAXEs 'hang' whilst waiting for the correct qualifier to arrive.

Hope this helps.