How many relays....

[Smokebreak]

How many DPDT 5V relays can I run one off one 5V reglated power supply? I'll have to look at what I'm using but it's either the Colossal or Granger setup.
Honestly I'm not sure how much the design of the power supply would affect things, as it relates to my ?? .
Also, what would be the issue? Voltage or current? I'll use the triad 6.3V lil tranny to power the system. I think it's 600mA or so. I could use 2 supply boards, in parallel, I guess? I need 5 dpdts, in all.

[sluckey]

It depends on the relay. The 5V relays that Hoffman sells require 40mA to operate. Five of those would only need 200mA. A 5V/1A supply would theoretically supply 25 relays even if all were energized simultaneously.

[R.G.]

How many DPDT 5V relays can I run one off one 5V reglated power supply? I'll have to look at what I'm using but it's either the Colossal or Granger setup.

At my former day job, the department secretary (yes, this was back when there WERE secretaries ) walked into the power supply lab and said "Hey, guys - what color is a capacitor?"

That relates to this question. The answer is "which capacitor", just as your answer is "Which relay, and which power supply?"

I have seen 5V **300ampere*** power supplies. I have seen relays that need several amps of current to pull in. I've seen relays that need 5V at about 25ma, too. So there isn't any good answer until you tell us which relays and which power supply. Otherwise, there are an infinite number of correct answers.

Honestly I'm not sure how much the design of the power supply would affect things, as it relates to my ?? .

Voltage regulation and current capability would matter.

Also, what would be the issue? Voltage or current? I'll use the triad 6.3V lil tranny to power the system. I think it's 600mA or so.

Hmmm. 6.3Vac gives 6.3*1.414 = 8.9Vpeak. You lose 1.4V to a rectifier bridge, giving 7.5V. That is **barely** enough to run a 7805 regulator, which needs 2V more on its input than it puts out. If the voltage sags even half a volt (like in a low-line condition, or a heavy load) the output will go under 5V.

Which may or may not matter to the relays. Some relays tolerate lower voltages, some don't, and some tolerate low voltages for holding better than for pulling in. Depends on which relay again.

I could use 2 supply boards, in parallel, I guess?

In general, paralleling regulated power supplies is a bad idea unless the power is quite small and a way to make them share the load is worked out. It gets tricky.

I need 5 dpdts, in all.

What kind, and what voltages and currents are they switching? Relays have limits on those.

The devil is **always** in the details.

[Aurora]

Dpending on the number of contacts needed, there are 5V DIP relays that operate on 7-8 mA.... only two closing contacts or one changeover, though

[John_P_WI]

Don't forget, not all of the coils need to be energized simultaneously.....

[Smokebreak]

Ok thanks fellas. Let me be more specific...
Here are the relays : https://nicegear.co.nz/obj/pdf/hk19f.pdf
I'm using the 5V ones, and all 5 DPDTs will be switching out AC signal. I've made care not to put HV DC on any contacts.

So this datasheet doesn't come right out and say it, but using the Law and the table, at 5V with 125Ohms resistance, we have 40mA current needed and .2A power spent. Correct? The only thing I don't quite understand is that this datasheet has multiple columns for diffwnt Power and Resistance??
For instance, here's the relay Doug H. uses : http://www.ece.usu.edu/ece_store/spec/G6A.pdf
You can see there is only one resistance per Voltage, and all Power consumption is .2W until you get to the 48V one.
I'm not understanding this. I mean, how is the resistance changing @ the same voltage?

Ok Power Supply:
Here's the trannies I use : http://www.mouser.com/ProductDetail/Tri ... nBPw%3D%3D
It's the Triad F13X, 6.3V @ 600mA, no CT
The actual prefabbed PS board I'm using looks fairly standard with a FWB package, a 7805, and 6600U filtering.

Sooo...I think I'm in the clear, but I'd like to hear from y'all about all this.