Hi friends,

Want to know if you had any ideas of off shelf signal relays, similar to the sainsmart relay board but with solid state relays. The SainSmart Board uses G1 transistors, 2n5551's. If I cant find a similar unit online Ill have to make one with solid state relays instead.

Now the issue with standard 5vdc solid state relay boards readily available is that the combined current draw exceeds 20ma.
I'm taking output signals from a 5vdc I/O circuit that is limited to 20ma across 16 channels, running them to the Sain Smart 16 ch Signal Relay board, which is then fed 5dc through NO to 16 external relays. I eventually need 32 inputs and 32 outputs.

I wish there was a device I can buy off the shelf that can take 16 input signals and be able to handle switching of 16 different relays rated 3 amps, on the other end.

If not I was thinking of using 2n5551's using the 5vdc 20ma max input signal, then running an aux 5vdc to power the relays. Any ideas, suggestions or question please ask away..

Thank you!!!
Chuck

 

What is a "sainsmart relay board"? Datasheet / website / anything?

Where are the relay control signals coming from?

What are the signals you are trying to switch? Voltage / current / frequency?

For us to evaluate your plan, post a schematic or wiring diagram of how you think things should go together.

ak

 

Hi Sorry this is the link to the board..

https://www.sainsmart.com/collections/internet-of-things/products/8-channel-signal-relay-module

 

The Relay control signals are coming from an NI 9264 FPGA module pushing vdc Voltage.

I have 16 resistor banks that need to be controlled via solid state relay using those Signals.

 

Your question is not very clear. I think you are saying that you already have a solution, but you don't like it:

FPGA > SainSmart relay board > power relays that can handle 3 A per circuit

Instead, you want to go directly from the FPGA to the output relays:

FPGA > power relays - you can't use the SainSmart board for this because its contacts are rated for only 2 A and you need 3 A

But those relays require too much control circuit current, so you want to use solid state relays:

FPGA > SSR

Is this correct?

What is the circuit that is being switched by the relays? Voltage / current / frequency?

ak

 

Haha, Yes. Sorry for the confusion. And I appreciate the response. I want to do something like this.

FPGA > Transistor Circuit > Relays

The relays im using now are SPC9694's that control heat resistors.

So a good (solid state) solution between the FPGA and The SPC9694's is my goal.

 

http://www.ti.com/lit/ds/symlink/uln2003a.pdf
http://www.ti.com/lit/ds/symlink/uln2803a.pdf

To switch 3 A, there are many smaller, lower cost DC SSR's available. Digi-Key has devices starting at $6.

https://www.digikey.com/products/en/relays/solid-state-relays/183?FV=a40154,a40155,1fc0001,1fc006c,1fc006d,1fc04f6,1fc04f8,1fc0080,1fc0503,1fc051c,1fc0084,1fc0010,1fc0002,1fc0016,1fc0004,1fc01ca,1fc01cc,1fc12e7,1fc021d,1fc021e,1fc0039,1fc003c,1fc003e,1fc028d,1fc1d58,1fc1df9,1fc1dfa,1fc1dfd,1fc0058,1fc0009,20800ed,mu10A|434,mu11.1A|434,mu12A|434,mu15A|434,mu16A|434,mu17.4A|434,mu17A|434,mu18A|434,mu20A|434,mu23A|434,mu24A|434,mu25A|434,mu4.5A|434,mu4.8A|434,mu4A|434,mu5.25A|434,mu5.5A|434,mu5A|434,mu6.5A|434,mu6.75A|434,mu6A|434,mu7A|434,mu8A|434,mu9A|434,1f140000,ffe000b7&quantity=&ColumnSort=1000011&page=1&stock=1&pageSize=500

Another option is the Opto-22 I/O system:
http://www.opto22.com/site/pr_details.aspx?cid=4&item=G4ODC5
http://www.opto22.com/site/pr_selector.aspx?cid=4&qs=100310071003#10111003
http://www.opto22.com/site/pr_details.aspx?cid=4&item=ODC5

If you are switching the bottom end of a DC load to GND, you can go directly from the FPGA to the output with one logic-level power MOSFET per channel.

https://www.ebay.com/itm/MOSFET-bre...487589?hash=item46374cc065:g:gJIAAOSwNdhZfhzo

Which raises a question: Do you need galvanic isolation between the control circuit and the load circuit?

Where are you located?

ak

 

Awesome! Thanks!

Any recommendations for a simple relay circuit I can make using a Transistor that can push a separate 5vdc supply into the SPC9694's.

FPGA signal> Transistor Relay Switch Circuit
(aux 5vdc supply fed into circuit above)
> 5vdc directed into Relays (x16)



No galvanic Isolation is needed

 

Any recommendations for a simple relay circuit I can make using a Transistor that can push a separate 5vdc supply into the SPC9694's.
No galvanic Isolation is needed

http://www.ti.com/lit/ds/symlink/uln2803a.pdf

2 pieces = 16 relay drivers; no other components required.

.OR.

Any reason why the MOSFET board linked above won't work for you?

.OR.

IF you want to build something with discrete transistors
AND IF you do not need galvanic isolation
THEN for each channel you can replace both the transistor driver circuit *and* the SSR with a single logic-level n-channel power MOSFET.

FPGA manufacturer and part number?
FPGA I/O supply voltage?

ak

 

Hey Thank you so much for your help. A 2803 has solved our problem. And works well!. We may be pushing some variable frequencies into it at various duty cycles. Will keep you updated. Thanks again!!!

 

N.I.National Instruments, will be happy to sell you everything to do what you want. They can do anything if you have enough money.

 

Almost true, but whatever you think is "enough money", you're wrong.

ak

 

I should have said "Lots of money", totaslly correct when dealing with NI.

 

Where did you come up with it takes 20 mA to turn on the relay.

At 5 volts it's .35mA that's not even a milliamp.



Too turn on all 8 only uses 8.3 mA

 

Hah! Because im killing the NI9264. Max output is 20ma.