Phidget dual relay 3051 with FEZ

Hello Guys,

a friend of mine gave me a fez domino with modules (led button piezzo speaker infra red, arduino ethernet shield etc…) I manage to make all of them working exept the phidget IO relay.
Then please have a look to the picture and Did I do something stupid with the wires??? or the relay is dead??? Please be aware that I am a developper and a bit / really stupid with the electronic but I would like to build a robot but first learn about .net micro and module capabilities.

The relay works when I change from NO to NC I guess the relay works… I also checked power from the back of the card, betwwen the the Control 1 and the black wire and I found 4.99V

If someone can help it would be really much appreciated thanks in advance!!!

Welcome to the forum!

NO is connected to VCC by default. Connecting to NO or NC is just a way to choose default state of the relay.

How do you connect it to the Domino?

relays consists of a coil and in this case a change over contact.

when the relay is not energised
common is open to the normally open contact
common is connected to or closed to the normally closed contact.

when the relay is energised
common is connected to the normally open contact [now known as closed]
common is open to the normally closed contact. [now known as open ]

to sumamrise the power you want to switch goes to the common. and then the output you want either; on when energised or; off when energised is connected to the coresponding n/o n/c contacts


I connect the 3Pin jack to domino DI4 configured as Output port ( I also check power and found the 3.3V) and then the the control 1 from the relay to 5V pin.
It is just a check after I guess I will need to connect the Control 1 to anothe DI/O in order to control properly the read but that would be step 2 :slight_smile:
basically I tried to reproduced the user guide found on the net 3051 User Guide - Phidgets Support


Hey there Corbal, welcome !

Awesome gift. Thank your friend again :slight_smile:

The relay is simply a “switch” controlled by another signal. The NO and NC markings represent “Normally Open” and “Normally Closed” which means, in the case of what I think your circuit is doing, it should mean the buzzer is normally OFF or normally ON respectively.

Here’s how I would diagnose what is going on. Note: I don’t have Phidgets gear or experience with them, so some of this may not actually work on Phidgets but I’m just basing this on my own general experience and expectation on how this all should work.

First I would prove that your buzzer works on it’s own, and that the battery is ok. Do that by disconnecting it from the relay contacts, and touch the wires. You should get your buzz. If not, or if it only works for a little while, you have a problem. If it works, great, move on.

Then I would connect one wire to the COMMON pole of the relay, without a control wire connected. Then touch the other wire on the NO contact briefly, then the NC contact. NO should not work, NC should work. Try that on both the 0 and the 1 relay, to prove they both work the same.

Then I would connect the relay in the NO position, so that it’s now not making a noise. Start with one relay and repeat the step on the other relay.

Then, power up your Fez, still with no control wire from a digital pin to the control line. Use a different jumper wire connected to a 3v3 line from Fez, touch that to the selected relay’s control pin. What that should do is simulate setting an output pin to TRUE, and then the relay should activate and the buzzer sound. Listen specifically for the relay to “click” as it activates. In case it doesn’t work, try touching the other relay control pin to see if it behaves the same or not.

If you don’t get the click, then the problem is most likely related to the activation current required for the relays. Can you tell us about what you’re powering the Fez with, I can see you have a plug in the barrel connector so give us the vital stats of the power supply itself (voltage and current capability).

@ Brett

Thanks for the answer. The buzzer and batterie are working I can hear it when I connect to NC.

As I Said I connected the 3 pin jack to DI4 output set to TRUE, then put the wire into the 5V fez pin and touch Control 1 or 0 but nothing.

the power supply is 5V, 500mA

I think you only need to connect ground from 3Pin jack (black wire) to the domino ground pin. Correct, you will be controlling relay through Control 1 using DI/O on Domino.

5v 500ma is probably not enough for your Fez anyway! Do the test directly connecting the relay control to 3v3 and see if you get the click. If not, I’d find a different power source as my first thing to try

Thanks for the answer but no luck. I check again the current at the back of the card between conrol 1 and black wire 4.98V, it means that the relay is energised no?? maybe not enough power… in that case do you know a relay that actually works with this Fez Domino?

Can you draw a simple diagram of how is everything is connected?

OK actually that makes sense. Could you please tell me the right setting V / mA please? and also do min / max a can put in a fez without damaging it?? Thanks a lot

@ Architect

I will draw it but I would like to give a try with another power supply then I repeat the question I asked to Brett,
Do you know the min / max power in V and mA I can put into the Fez domino to make it works without any damage for the board…?

thanks a lot for you time. appreciated

You really need 6.5v as a minimum on an external power supply that then is supplied into the voltage regulators on the device, which then creates a 5v and 3.3v supply for the components on the board. Edit: The maximum rated supply on a Domino is 12v as shown on the silkscreen, but personally I would try to keep that to 9v; there’s heat generated as the voltage is lowered, so it’s preferable to keep it at the lower end of the voltage range if you can.

From a power consumption perspective, you never “force” current into a device, it always draws as much as it needs. If the power supply can’t give it enough, you usually end up with the supply “browning out” and the foltage dropping to a point where things become unstable. So you can’t have too much power here.

Personally, I would try to get a power supply that has 6.5V 1000mA (which is 1A, but you could go more if you can find one).

But lets get back to the relay. Do you have a power supply you can use on the Phidgets relay board? I think what the next test I would do is keep Fez out of the picture. You need to supply GND and VCC (5v would be fine) to the board, then connect VCC to the control pin on a relay. That should trigger it to click.

@ architecte, hereby the diagram

@ Brett. I do not have such a power supply the only thing I have is the 9V batterie…

the problem isn’t positive/negative on the battery.

To use this relay you need to supply a GND and a VCC to the phidgets board, and then you need a separate “control” line. You don’t have a VCC line !

You’re also going to have to look to buy a power supply that is better for this purpose…

Too bad they don’t have schematics for that board. I am not sure if it is applicable here but these relays also need minimum load current to work (100mA).

Take a look at the user guide you linked to. The cable marked “4” is the one you need to replicate from your Fez, although you don’t need the “analog in” wire (I don’t believe). So that’s the red and black wires, make sure you connect them to the 5v (or 3v3) and GND respectively. Then connect from the same wire (5v or 3v3) to the C0 and C1 connectors and the relay should click

Do they have something extra on that board to power it from VCC?

their so called “analog input” wire, marked as 4 in one of the images, has Analog In then VCC and GND. They say 5v. Then there’s a separate IO wire that controls the switching. The test I want to do, is with the 5v and GND powering the whole board, connect 5v to the control pin, the relay should engage.