I hope someone can help.
I want to drive 16 24VAC 3-wire relays, one at a time, for about 250ms each.
Each relay has a common wire, an on wire, and an off wire.
They latch into the last chosen mode, on or off.
The inrush current is 350mA.
The relays control 120v lighting, if you are curious.
Data sheet (attached) shows that they will actually have a longer life if the voltage is half rectified.
How feasible is that with an Uno?
I'm thinking of using 2 stacked 4x4 driver shields, one for on mode and one for off. Or maybe some type of relay board could be used instead.
Any suggestions on this are appreciated.
Thanks!
Like LarryD says, the data sheet says you can drive it with 30v DC. Remember, Arduino CANNOT touch that. I would think you want the Uno to drive a MOSFET that can handle the voltage and switch the relay. Blue wire of the relay to 30v. Low-side switch with one N channel MOSFET on the red and one on the black. Maybe just a 2N7000. Write out to a transistor to change relay state. I think pull down resistors.
bigred1212:
Like LarryD says, the data sheet says you can drive it with 30v DC. Remember, Arduino CANNOT touch that. I would think you want the Uno to drive a MOSFET that can handle the voltage and switch the relay. Blue wire of the relay to 30v. Low-side switch with one N channel MOSFET on the red and one on the black. Maybe just a 2N7000. Write out to a transistor to change relay state. I think pull down resistors.
Thank you. I appreciate your reply as well as that of LarryD.
I need to drive up to 16 of the relays, so I will have to figure out how to sequentially activate 16 of the "on" or "off" MOSFETS.
If you know how that can be done, I'd be grateful for the information.
Initially, I was planning on using a pair of Logos Electromechanical's 4x4 Driver Shields (manual attached).
However,they top out at 30VDC, and I am unsure as to whether they will allow AC.
Even if they will switch partially rectified AC voltages, I'm concerned that the peak AC voltage will be above 30v
Again, If you or anyone else has any more input on any part of this project, I would greatly appreciate it.
MikeyDude:
I need to drive up to 16 of the relays, so I will have to figure out how to sequentially activate 16 of the "on" or "off" MOSFETS.
Initially, I was planning on using a pair of Logos Electromechanical's 4x4 Driver Shields (manual attached). However,they top out at 30VDC, and I am unsure as to whether they will allow AC.
They would be perfect for the purpose. Albeit a bit expensive, but having been reminded and now that they are back in stock, I have a mind to purchase two for my home lighting system (to drive relays, but not the holding relays as you intend).
MikeyDude:
Even if they will switch partially rectified AC voltages, I'm concerned that the peak AC voltage will be above 30v
30V DC is within the rating of the IPS6044 chips used (36V absolute maximum, recommended up to 28V) and should be OK given that you are switching a load far less than the maximum currents and for very short periods (300 ms). If you wish to use rectified AC, then full-wave rectified 24V (but absolutely no more) without a smoothing capacitor would still be within the 36V limit. 22VAC rectified and smoothed would give about 30V.
As to your code, you will need the shift function previously described to write and latch the data to the shield, and you arrange to set up the data sequence desired in two bytes for each step, then write those bytes using the shift out function. At each sequence step, you need to write out a "zero" pair of bytes 300 ms later or (at the expense of an extra port used) simply use the "Master Reset" and re-latch.
it would seem the selected relays are very expensive.
a SSR should work in the application and you can get 5v siganl inputs on 30A SSR's
take a look at shift registers. lots of information on how to use them with an Arduino and they add a layer of protection between the relay and the Arduino.
Grumpy_Mike:
With 20 pins avaliable on an arduino why do you need anything else. You do know the analogue input pins can be used as digital outputs?
My problem for the home lighting is subtly different; as I wish to drive 32 relays, so I was always committed to using a SPI system. I have had the basic shift register boards as such laying in wait for some 20 years now! =( The problem has always been a well-constructed buffer board to control the relays - just that array of FET drivers, 16 at a time. Even now, there are relay boards advertised with 1, 2, 4, 8 and 16 relays and such, but I already have the relays, to be mounted with sockets on a standard electrical control box DIN rail system. The "Logos" boards are the only plausibly priced (and expensive even then) relay driver-only boards that I have ever been able to find.
Getting anxious on this project (and my wife much more so) - and actually spotted my licensed electrician mate from the project 20 years back yesterday, but he was getting surprisingly friendly with a lady at the moment and waved me off telling me he could not talk.
For under a buck you drive the four inputs to select the target relay with four D lines, and strobe the single selected output high with a fifth. A second 4514 in parallel on the inputs enabled by a 6th D line on the Arduino can do the off duty.
The outputs can directly drive gates on any number of common FETs or use IC buffer ICs. A 'two chip solution' with a bunch of cheap driver channels (Transistor or IC as you wish). Uses 6 D output lines, none special.
RetiredGuy:
Lots of cool 4 to 16 decoders out there, like say CD4115:
For under a buck you drive the four inputs to select the target relay with four D lines, and strobe the single selected output high with a fifth. A second 4514 in parallel on the inputs enabled by a 6th D line on the Arduino can do the off duty.
The outputs can directly drive gates on any number of common FETs or use IC buffer ICs. A 'two chip solution' with a bunch of cheap driver channels (Transistor or IC as you wish). Uses 6 D output lines, none special.
There are a few complications, which affect both the OP and myself.
It mostly has to do with the job of assembling those 32 driver FETs or 4 buffer ICs as well as the 4514s, in a less than Heath-Robinson setup which will be acceptable in a domestic wiring installation.
In Arduino programming terms, it is actually much easier to use shift registers with any reasonable number chained from only three pins, you actually only need four TPIC6B595 chips to drive 32 relays.
Paul__B:
In Arduino programming terms, it is actually much easier to use shift registers with any reasonable number chained from only three pins, you actually only need four TPIC6B595 chips to drive 32 relays.
I have a serial board/relay for 4 relays and output for 4 more. what I had to stumble around with is that much of my external relays are 24VAC or 120VAC. I finally decided to just use smaller relays and then use them to power the larger external relays.
by using 24VAC, I can use low voltage wiring and not have to deal with metal conduit and such. (commercial applications)
I can put the larger relays in the metal enclosure and the logic in a remote location.
I think the reason you have not found a good fit is that there are just too many variables.
dave-in-nj:
I finally decided to just use smaller relays and then use them to power the larger external relays.
by using 24VAC, I can use low voltage wiring and not have to deal with metal conduit and such. (commercial applications) I can put the larger relays in the metal enclosure and the logic in a remote location.
I do want to keep the control equipment small and locate it with a divider in the same control box (and it is not a small one). One of my criteria is that if the mains fails, the control circuitry should draw virtually no power from the backup battery.
dave-in-nj:
I think the reason you have not found a good fit is that there are just too many variables.
I think it is just that my requirement is neither "hobbyist" and therefore offered as a "project" board, nor "commercial" and attracting a high premium. The "Logos" boards are in my category, but very expensive for the function. In retrospect, I think I will just go with the TPIC6B595s which execute the function perfectly and concisely and assemble them on a quality (glass fibre) "protoboard" of some kind.
Arguably that is of course, what MikeyDude should do as well - the TPIC6B595 has a lesser current rating but quite adequate, and a more generous voltage rating - and twice as many outputs as the IPS6044.
dave-in-nj:
I finally decided to just use smaller relays and then use them to power the larger external relays.
by using 24VAC, I can use low voltage wiring and not have to deal with metal conduit and such. (commercial applications) I can put the larger relays in the metal enclosure and the logic in a remote location.
I do want to keep the control equipment small and locate it with a divider in the same control box (and it is not a small one). One of my criteria is that if the mains fails, the control circuitry should draw virtually no power from the backup battery.
dave-in-nj:
I think the reason you have not found a good fit is that there are just too many variables.
I think it is just that my requirement is neither "hobbyist" and therefore offered as a "project" board, nor "commercial" and attracting a high premium. The "Logos" boards are in my category, but very expensive for the function. In retrospect, I think I will just go with the TPIC6B595s which execute the function perfectly and concisely and assemble them on a quality (glass fibre) "protoboard" of some kind.
Arguably that is of course, what MikeyDude should do as well - the TPIC6B595 has a lesser current rating but quite adequate, and a more generous voltage rating - and twice as many outputs as the IPS6044.
Wow, I don't even know how to reply to all the posts.
Thank you for all the input.
I'll have to take a longer look at the thread to be able to really "get" all of the suggestions.
SSRs look really good. Shift registers will be a must with them.
Paul__B,
I think you understand that I will need to activate the "off" side of up to 16 of the GE relays, and the "on" side of the same 16 relays.
There is no special sequence that I want to use.
I just want to turn off the GE relays one at a time so as to not overload the modest sized 24v transformer.
I am a bit concerned about the TPIC6B595 max current specs, though.
Especially in the data sheet notes regarding current rating.
You are suggesting driving the GE 24v relays directly with this, correct?
