Using Relay to Power on Device

Thread Starter

Andedam

Joined Jul 30, 2020
10
Hello

I am currently struggling a lot with a task, where I must power on a device using the internal relay, For this I use the Agilent Technologies 34980A Multifunction Switch/Measure Unit

My device takes as input 5V and 1.3A


I am uncertain whether these relays output voltage to power on the device, or if I must power it on separately, and then use the relays as 'middleman' to let power through or not.

Thanks in advance! BR Andedam
 

Thread Starter

Andedam

Joined Jul 30, 2020
10
I assume you are using the 34937A general purpose switch module in the 34980 mainframe. The use manual should have all the information you need:
https://www.manualslib.com/manual/555622/Agilent-Technologies-34937a.html?page=5#manual
Regards,
Keith
Thank you very much for the response. I find that I have looked through the datasheet, and given it a shot to work around with my D-sub 50 connector, but without luck - I can't seem to get the device turned on using the relay.

If I may share my process of thought;

Since I can't seem to output 5V from my AT 34980A MF Switch, I am using an arduino to do this. Besides this I have configured the interface with LabView, from which I can turn on/off the relays.

I also have the device, with the PCBA board extracted and ready to wire up.

I am very uncertain about how I should set this up, as it doesn't seem to work. Am I understanding this correctly, that I should only use a single pin from the D-Sub 50 to set it up? Please enlighten me :/

THANKS in advance! BR Andedam
 

KeithWalker

Joined Jul 10, 2017
1,019
The 34937A is just a switching unit. It just contains 28 form C relays and 4 form A relays. It does not provide power to the contacts. You can check if the relay you are selecting is opening and closing its contacts by checking for continuity through them on the D-sub connectors.with a multimeter.
Keith
 

Thread Starter

Andedam

Joined Jul 30, 2020
10
The 34937A is just a switching unit. It just contains 28 form C relays and 4 form A relays. It does not provide power to the contacts. You can check if the relay you are selecting is opening and closing its contacts by checking for continuity through them on the D-sub connectors.with a multimeter.
Keith
Hi again

Thanks for the tip. I did check for continuity with the DMM, and it’s all good.

I think I am struggling with the setup. If I use the 5V output from the arduino, how should this be set up according to the relay(s)?
Somehow the relay has to come in play between the Vin on the PCBA board of the device and the arduino’s 5 V output. I cant Seem to comprehend this /:

Sorry for the stupid questions..
BR Andedam
 

Thread Starter

Andedam

Joined Jul 30, 2020
10
Make sure the GND on the arduino is connected to the supply common on the PCBA board or nothing will happen. Have fun.
Keith
Hi again, thanks for the follow up.

What I did was like on the picture, as well as connecting the ground from the Arduino' to the ground from the 34937A as well as the ground from the PCBA board. And then taking the 5V output from Common Relay'. The PCBA board does not have any LEDs to illustrate it's turned on', but I suppose it's working ?

BR Andedam
 

KeithWalker

Joined Jul 10, 2017
1,019
I just noticed in your first posting that the PCBA takes 1.3A. The form C relay contacts are only rated at 1A so use one of the form A relays (channels 001,028,029 or 032). If you repeatedly switch one of the form C relays with 1.3A on the contacts, the contacts will eventually weld together.
I have no idea what your PCBA is so all I can suggest is that you check with a voltmeter between 5V and GND on it to make sure the power is getting to it.to it.
Keith
 

Thread Starter

Andedam

Joined Jul 30, 2020
10
I just noticed in your first posting that the PCBA takes 1.3A. The form C relay contacts are only rated at 1A so use one of the form A relays (channels 001,028,029 or 032). If you repeatedly switch one of the form C relays with 1.3A on the contacts, the contacts will eventually weld together.
I have no idea what your PCBA is so all I can suggest is that you check with a voltmeter between 5V and GND on it to make sure the power is getting to it.to it.
Keith
Yeah, Thanks. I did notice that, and went with the form A relays. What happens if the form A relays are cappen at 1 A and the PCBA requires 1.3? Any solution here?

Also I am uncertain about the NC pin. What are we using this for?

BR Andedam
 
The form A relays are rated for 5A so they are safe for you to use with 1.3A.
Form A relay contacts are just a pair of contacts that are normally open when the relay is not powered.
In form C contacts the armature(C) makes contact with the normally closed (NC) contact when the relay is not powered. When the relay is powered, the armature (C) moves from the normally closed (NC) contact to the normally open (NO) contact.
If you used the form C contacts just to power something, the NC contact is not used.
Keith
 

Thread Starter

Andedam

Joined Jul 30, 2020
10
The form A relays are rated for 5A so they are safe for you to use with 1.3A.
Form A relay contacts are just a pair of contacts that are normally open when the relay is not powered.
In form C contacts the armature(C) makes contact with the normally closed (NC) contact when the relay is not powered. When the relay is powered, the armature (C) moves from the normally closed (NC) contact to the normally open (NO) contact.
If you used the form C contacts just to power something, the NC contact is not used.
Keith
Ahh alright, thanks! How do you know by certainty that these are the form A relays? (channels 001,028,029 or 032)

When I look at the "34937A D-Sub Connectors Bank 1" connection below, and keep in mind that the form A relays only use an NO and COM, I struggle to see why channel 1 (pin 8, 25, 42) should be 5A Form A

1596375876769.png



Also this might be a dumb question, but must I do anything regarding the 1.3 A other than using the form A relays rated at 5 A?
 
(QUOTE)
Ahh alright, thanks! How do you know by certainty that these are the form A relays? (channels 001,028,029 or 032)
(QUOTE):

See page 12 of the attached 34937A manual:

The 34937A general- purpose switch module provides independent control
of:
• Twenty- eight Form C (SPDT) latching relays rated at 1 A
• Four Form A (SPST) latching relays rated at 5 A.

On the same page are diagrams of the different contacts.

(QUOTE)
Also this might be a dumb question, but must I do anything regarding the 1.3 A other than using the form A relays rated at 5 A?
(QUOTE);

I have no idea what you are trying to do with the 34937A for or what your "PCBA" is. If you explain what your task is I may be able to offer some suggestions.
Keith
 

Thread Starter

Andedam

Joined Jul 30, 2020
10
(QUOTE)
Ahh alright, thanks! How do you know by certainty that these are the form A relays? (channels 001,028,029 or 032)
(QUOTE):

See page 12 of the attached 34937A manual:

The 34937A general- purpose switch module provides independent control
of:
• Twenty- eight Form C (SPDT) latching relays rated at 1 A
• Four Form A (SPST) latching relays rated at 5 A.

On the same page are diagrams of the different contacts.

(QUOTE)
Also this might be a dumb question, but must I do anything regarding the 1.3 A other than using the form A relays rated at 5 A?
(QUOTE);

I have no idea what you are trying to do with the 34937A for or what your "PCBA" is. If you explain what your task is I may be able to offer some suggestions.
Keith
Ohh Thanks, I must have missed that diagram.

My task sounds rather simple;

Use the A34980 to Power On a device.
So I found this device (external speaker) that takes as input 5 V and 1.3 Ampere

I have set up the LabView interface, from which I can turn on/off the relays. So now I just need to set this up circuit-wise, I think.

So I thought about using an arduino for this, supplying the device with 5 V (4.78 V measured from arduino)
P
How do the 1.3 Amp fit in here in this place?

BR Andedam
 

Thread Starter

Andedam

Joined Jul 30, 2020
10
I just noticed in your first posting that the PCBA takes 1.3A. The form C relay contacts are only rated at 1A so use one of the form A relays (channels 001,028,029 or 032). If you repeatedly switch one of the form C relays with 1.3A on the contacts, the contacts will eventually weld together.
I have no idea what your PCBA is so all I can suggest is that you check with a voltmeter between 5V and GND on it to make sure the power is getting to it.to it.
Keith
Just making sure.. Now I realised those dots meant from 1 ... til 28.
Just to be sure, the channels 001 and 028 are 1A Form C and the 5A Form A channels go from 029 to 032.
I was just confused because you reference both channel 001 and 028 in your parenthesis.

BR Andedam
 
So I thought about using an arduino for this, supplying the device with 5 V (4.78 V measured from arduino)
P
How do the 1.3 Amp fit in here in this place?

BR Andedam
An Arduino is NOT a good choice to source 5V for your speaker.
How are you powering the Arduino?. If you are using 7 to 12 volts on the VIN pin you are limited to 500mA out of the +5V pin. More than that will overload the regulator chip on the arduino.
If you are supplying the Arduino from a USB outlet, the maximum current you can take from the +5V pin is the max current the USB can supply (depending on USB version) less 40mA that will be used by the Arduino, less any other current taken from any Arduino output pin.
If you are supplying 5V from any external supply then you are limited by what current it can supply.
Keith
 

Thread Starter

Andedam

Joined Jul 30, 2020
10
An Arduino is NOT a good choice to source 5V for your speaker.
How are you powering the Arduino?. If you are using 7 to 12 volts on the VIN pin you are limited to 500mA out of the +5V pin. More than that will overload the regulator chip on the arduino.
If you are supplying the Arduino from a USB outlet, the maximum current you can take from the +5V pin is the max current the USB can supply (depending on USB version) less 40mA that will be used by the Arduino, less any other current taken from any Arduino output pin.
If you are supplying 5V from any external supply then you are limited by what current it can supply.
Keith
I am using USB from a PC to the arduino. I suppose I have been supplying the device wrong. Do you have any suggestions on What might be the right approach?

The device has a USB-C connector to power it on. How is it different using the USB C directly to the computer to power it on, instead of using the arduino as power source? Because of The current? What can I use them?

BR Andedam




The device c
 
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