# Need Electronic Substitute For Relays



## Mark R. (Jan 26, 2013)

Quick background .... My room lights are on a motor driven dimmer. As the room lights come down I have a circuit with four photocells that detect four different levels of light. Each photocell circuit turns a relay on / off which controls a more robust power supply that runs my structure lights. This way, as the room lights come down, the structure lights come on randomly depending on which relay circuit they are attached to.

There are two sets of relays like this for a total of eight relays. They are a typical SPST 12 volt solenoid relay. What I don't like is as each one turns on, there is that distinct snap of each one turning on .... which I find very annoying. Visitors even ask what the noise is.

Finally, my question .... is there something electronic that I could replace these solenoid relays with ? They function on a relatively low current 12 volts, and control a 20 amp 12 volt supply (currently only providing about 2 amps of load, but will increase over time as more lights are added). Would really like this to function with no noise in the room.

I had even thought of even moving the relays outside the room, but that would just be inconvenient.

Mark.


----------



## J.C. (Dec 24, 2016)

a SCR


----------



## Mark R. (Jan 26, 2013)

J.C. said:


> a SCR


Well .... I *think* that stands for Silicon Controlled Rectifier. (?) 

And that's about all I know. I don't know what it looks like, what variation I would need or even more important - even begin to know how to wire one up for my application.

*Thanks* for your help .... 

Mark.


----------



## Mark R. (Jan 26, 2013)

Sticking with something I understand .... would these solid state relays be use-able ? ....










My control voltage of 12 VDC looks appropriate. Just wondering about the 240 VAC load rating. What is the DC amperage equivalent of 12 volts to 2 amps at 240 VAC ? Using this calculator ....

https://www.batterystuff.com/kb/tools/ac-to-dc-amperage-conversion-run-through-an-inverter.html

.... I get a result of 44.16 amps at 12 volts DC is equivalent to 2 amps at 240 volts AC - is that right ?

Mark.


----------



## wvgca (Jan 21, 2013)

Solid state relays are rated not only by current, but by intended type of voltage ..both input and output .. 

the one you show will switch up to 2 amps, no more, and AC up to 240v ..
and there are internal differences between those designed for AC or DC switching, 

There are also solid state relays the will switch either AC or DC, and are labelled as such ..but are normally used for under a 10A load 

So for your use, a DC or AC/DC SSR would be applicable ..

The current rating would be your maximum intended current .. with another consideration, the 'surge' current ... for led's it 1:1, but for incandescent it can be as much as 6:1 ....depends on the type of lights tha you have in your structures 

but there is no noise involved during use .. Omron is one of the better known name brands

If you have incandescent bulbs, here's a link to the TYPE that may work well for you ...turns on with 3-32V DC, and switches DC loads of 5-120V at up to 10A, if your lights are LED's, a lot smaller current rating would work

http://www.ebay.ca/itm/1pc-KYOTTO-D...hash=item1ebe543f84:m:msmKT3FKfcXjFz4W9j_OeUA


----------



## redman88 (Nov 25, 2015)

I would suggest that instead of switching on the whole power supply you put the relays on the output side of the power supply. One sensor controlling several relays that have fuses inline on the load side.


----------



## gregc (Apr 25, 2015)

Mark R. said:


> Finally, my question .... is there something electronic that I could replace these solenoid relays with ? They function on a relatively low current 12 volts, and control a 20 amp 12 volt supply (currently only providing about 2 amps of load, but will increase over time as more lights are added). Would really like this to function with no noise in the room.


have you considered a MOSFET driven circuit. It would be similar in concept to an SCR, but not latching.

Sounds like you have groups of lamps/LEDs powered thru a relay, presumably providing power. They could all be tied to V+ and the ground connection for each group tied to ground thru a MOSFET. Applying a + gate voltage will turn on the MOSFET.

I believe you know that there is very little voltage across the MOSFET when it is conducting, so little need for a heat sink. This is similar to how they are used in PWM throttles.


----------



## wvgca (Jan 21, 2013)

Mark, 
when you mentioned that you control a more robust power supply, I 'assumed' that you were controlling the DC OUTPUT, and that's why I went that way ... 
If you are actually controlling the AC INPUT, the SSR you pictured would be fine ..and much lower in cost compared to the ones that I linked to


----------



## gregc (Apr 25, 2015)

wvgca said:


> If you are actually controlling the AC INPUT, the SSR you pictured would be fine ..and much lower in cost compared to the ones that I linked to


Aren't TRIAC's needed for AC power and won't they require both + and - trigger voltages, therefore a triac optocoupler?

Not recommending this approach. Agree with others to control the low voltage DC output.


----------



## wvgca (Jan 21, 2013)

gregc said:


> Aren't TRIAC's needed for AC power and won't they require both + and - trigger voltages, therefore a triac optocoupler?
> 
> Not recommending this approach. Agree with others to control the low voltage DC output.


Yes, in general SSR's for switching AC use this type of internal construction, and can be obtained in either zero crossing trigger or random, depending on the intended application, while DC SSR's in smaller sizes commonly use MosFet's, and a SSR marked for AC/DC will normally have no issues switching either AC or DC up to their current limit, usually under 10A..

In my opinion, switching the low voltage DC is safer in most cases, and for most users .. 

The 'puck' style of SSR that I linked to is a higher current capability and is commonly used in industrial control ..and that one was around $8, the one that Mark showed should be around $1, big difference in price if you need a lot of them ..
The smaller ones are also readily available pre-wired modules that can have 2/4/8 individual relays mounted ..for around $1.50 / SSR ..
I use those in 4 or 8 bank modules for sprayer section control with automatic GPS control for chemical application ..


----------



## gunrunnerjohn (Nov 10, 2010)

I hate to suggest the obvious, but why not simply sound insulate the relay box and/or substitute other quieter relays? I use relays that I have to get my ear down near the relay to hear them activate, surely they wouldn't be obnoxious.

I use these on a signal board, certainly cheap enough at 50 cents each and free shipping.

5Pcs Mini HK19F-DC12V-SHG 1A 125V AC 2A 30V DC Power Relay 8Pin Coil DPDT


----------



## Mark R. (Jan 26, 2013)

Yes, just to clarify, I am controlling the 12 volt DC output of the power supply, not the AC line voltage.

I'm currently using a low power 12 volt supply to control the photocell circuit which also powers the the relays. The relays are controlling the 12 volt output of the power supply I'm using to power the building lights - which are 99% LEDs.

This set-up was originally built some 20 years ago. Due to location convenience, I paralleled the four original relays to another group of four relays controlling a new power supply at the other end of the room, so now as the room lights come down, each photocell now turns on two relays. I don't like the noise these last four are making. The original four are in a more isolated location and aren't as noticeable. 

It's possible that there are more quiet relays as this last four are rather noisy in their operation - just not real keen on ordering dozens of relays just to find the quietest ones.

Ultimately - based on how many lights are currently in use, each relay will probably never have much more than 1 to 2 amps ever flowing through it, if that.

Mark.


----------



## wvgca (Jan 21, 2013)

any solid state relay has no moving parts ... no noise, a bit more money than solenoid type, but will last virtually forever ..
I do like john's idea of just putting a sound deadening enclosure over them, quickest solution


----------



## gunrunnerjohn (Nov 10, 2010)

Mark R. said:


> It's possible that there are more quiet relays as this last four are rather noisy in their operation - just not real keen on ordering dozens of relays just to find the quietest ones.


I just posted some very quiet relays, so I can't imagine what else you need. Why would you have to buy multiple batches of relays? If you simply don't want a relay solution, why not say so?


----------



## J.C. (Dec 24, 2016)

Mark R. said:


> Well .... I *think* that stands for Silicon Controlled Rectifier. (?)
> 
> And that's about all I know. I don't know what it looks like, what variation I would need or even more important - even begin to know how to wire one up for my application.
> 
> ...


a 12 amp will be the largest I would think you need tada has them for less than 50 cents if you could get by with 5 amp they run less than 15 cents, wiring is simple like a relay check on line to find circuit for them your photo cell would turn on the gate.


----------



## gunrunnerjohn (Nov 10, 2010)

J.C. said:


> a SCR


An SCR is not an appropriate tool for this task. Once the SCR is turned on, the voltage has to be externally removed to turn it back off. They are commonly used for the crowbar P/S shutdown for that reason. For AC a triac would do the trick, for DC something like a power FET would be suitable.


----------



## Lemonhawk (Sep 24, 2013)

I'm in John's camp on this. Those are really quiet relays. Just make sure you don't try to run more than 2 amps of DC thru them. You may need to separate the circuits a little more to get them under 2 amps. They are also DPDT relays so each would handle 2 circuits of 2 amps each.


----------



## Mark R. (Jan 26, 2013)

gunrunnerjohn said:


> I just posted some very quiet relays, so I can't imagine what else you need. Why would you have to buy multiple batches of relays? If you simply don't want a relay solution, why not say so?


I'm not 100% against mechanical relays - as a matter of fact, I use some relays that look identical to the orange ones you posted for my signalling system. Could be the fact they are mounted to the wall of the benchwork that the sound is somewhat amplified. I have the circuit boards mounted on rubber bushings which helps. I've been accused of having overly sensitive hearing, so that may have something to do with it as well. 

I would really like to eliminate any noise altogether. The solid state relays posted earlier in the ebay link look promising.

Mark.


----------



## gunrunnerjohn (Nov 10, 2010)

If you're using a relay anything close to what I show, it should be trivial to deaden any sound from it. I set this on a chunk of thin fiberglass 12" x 6" suspended at the ends and operated the relay. I could barely hear the relay a couple feed from it, I can't believe anyone would hear this from a few feet away, even with dog ears.

However, I get it, you don't want a relay, I'll stop making suggestions.


----------



## Mark R. (Jan 26, 2013)

C'mon John, don't be like that. As I said, I have very sensitive hearing and What you find barely audible, I may find annoying. 

For the record, I have 43 (I went and counted) of those little orange relays used in controlling my signaling system, and I do hear them every time one is activated. If I were designing a signal system today, I'm certain I would do it different to eliminate the relays, but that's what I found would do the job when I built it 25 years ago.

Moving forward my preference is to do things "better" than I had in the past, which to me, means eliminating all that annoying clicking. Would love not to hear a click every time a train enters or leaves a block, but to rip out an entire winter's work - not to mention what seems like miles of wire - is just not very enticing, no matter how much I dislike the clicking. To me, it's like cracking knuckles, tapping fingernails, etc. .... just plain annoying. I can even hear digital displays singing which I find really annoying. I once sold a car after only two months because the digital gauges made a high frequency sound that drove me nuts - and to make matters more frustrating, nobody else could hear what I was complaining about.

Mark.


----------



## J.C. (Dec 24, 2016)

gunrunnerjohn said:


> An SCR is not an appropriate tool for this task. Once the SCR is turned on, the voltage has to be externally removed to turn it back off. They are commonly used for the crowbar P/S shutdown for that reason. For AC a triac would do the trick, for DC something like a power FET would be suitable.


would a GTO work then.


----------



## Mark R. (Jan 26, 2013)

J.C. said:


> would a GTO work then.


Well, there's one Google doesn't even help me with. 

Mark.


----------



## gunrunnerjohn (Nov 10, 2010)

That one comes out of left field! 

The GTO is a high power device as a rule, and it's not commonly found in a typical parts supplier's inventory. I personally have never even seen one. Judging from the picture, I'd say it's probably overkill for this application. Maybe we can come down to earth now. I'm sure of one thing, it'll handle whatever power he needs, up to and including switching his main power panel on and off!

S6728GXH(Strom-B) – Toshiba, Gate Turn Off Thyristor (GTO), only $275.


----------



## Mark R. (Jan 26, 2013)

At this point, after extending Warren's suggestion, I came across these that are reasonably priced ....

http://www.ebay.ca/itm/New-Plastic-...613905?hash=item1a1e20c591:g:bPwAAOSwJ7RYT2Vl

.... the specs appear to be in well within range for my application. (?)

Mark.


----------



## redman88 (Nov 25, 2015)

Fun times when you fuse one of these in the closed position. 

https://www.google.com/search?rlz=1...0k1j33i21k1.lKBGQP0vNXU#imgrc=mPY8i-14KXFhdM:

Once you do that you tend to fuse the main power disconnect in the closed position as well.


----------



## wvgca (Jan 21, 2013)

redman88 said:


> Fun times when you fuse one of these in the closed position.
> Once you do that you tend to fuse the main power disconnect in the closed position as well.


I have similar in some tractors out at the farm, mine are called series / parallel switches..a fancy hundred dollar solenoid, .In parallel they run 2 1750 ca 8d batteries for usual stuff, for starting the engine they flip to series mode, gives 1750 amps at 24 volt.. warms up the cables a tad ..and series output works very well as a portable emergency stick welder


----------



## redman88 (Nov 25, 2015)

We use them to run a motor. Typically run 56v through them as that's what the batteries stay around when the solar charge system is working.


----------



## Lemonhawk (Sep 24, 2013)

Well there is always a Thyratron. that's a gated vacuum tube. We experimented with them when I was going to engineering school. I still like John's relays, Seems like SSR's would have more internal resistance.


----------



## Tom_C (Jan 8, 2016)

Mark R. said:


> because the digital gauges made a high frequency sound that drove me nuts - and to make matters more frustrating, nobody else could hear what I was complaining about.
> 
> Mark.


Oh, I get it now. You're a Wookie!

Kidding.


----------



## wvgca (Jan 21, 2013)

redman88 said:


> We use them to run a motor. Typically run 56v through them as that's what the batteries stay around when the solar charge system is working.


Halliburton got a pretty good image boost by using solar instead of diesel motors to run the sand silo's ... good idea..


----------



## gunrunnerjohn (Nov 10, 2010)

Mark R. said:


> At this point, after extending Warren's suggestion, I came across these that are reasonably priced ....
> 
> http://www.ebay.ca/itm/New-Plastic-...613905?hash=item1a1e20c591:g:bPwAAOSwJ7RYT2Vl
> 
> ...


I have some similar switches from that product line, mine are the AC variety.


----------



## redman88 (Nov 25, 2015)

wvgca said:


> Halliburton got a pretty good image boost by using solar instead of diesel motors to run the sand silo's ... good idea..




Good idea piss poor execution.


----------



## wvgca (Jan 21, 2013)

Mark .. did you know that you can get proportional solid state relays.. where a variable DC in will give a variable output ... not just ON/OFF ...
the drawback is that [as far as I know] they vary AC only, not DC ..and not real cheap either ..and probably not suitable to your needs ..


----------



## Lemonhawk (Sep 24, 2013)

Seems like the solar collectors would work a lot better had they been put in the sunlight instead of the shadow?


----------



## highvoltage (Apr 6, 2014)

Mark R. said:


> ...As I said, I have very sensitive hearing and What you find barely audible, I may find annoying...


http://www.hyperacusis.net/what-is-it/4-types-of-sound-sensitivity/


----------



## redman88 (Nov 25, 2015)

Lemonhawk said:


> Seems like the solar collectors would work a lot better had they been put in the sunlight instead of the shadow?




There are two sets. But yes they are poorly placed. But the 4 massive batteries compensates some what and the little power draw needed while in operation. If the batteries are dead there is a jumper cable to get power from the one next it. Also there are hydrologic lines for setting up and taking down if the electric motor won't work.


----------



## time warp (Apr 28, 2016)

If the entire issue is the noise, go the other way and add some. Keep a small fan running near the trouble spot, the "white noise" may be the solution.


----------



## wvgca (Jan 21, 2013)

Mark R. said:


> At this point, after extending Warren's suggestion, I came across these that are reasonably priced ....
> 
> http://www.ebay.ca/itm/New-Plastic-Metal-Solid-State-Relay-SSR-DC-DC-25A-3-32VDC-5-60VDC-AD-/112174613905?hash=item1a1e20c591:g:bPwAAOSwJ7RYT2Vl
> 
> ...


It's been a month...
Did you find a solution that you are happy with??


----------



## Mark R. (Jan 26, 2013)

Well, I ordered some from one of those ebay China sellers, and after a month, they still hadn't showed up. After complaining enough, the seller refunded my money and I re-ordered them from a different seller in China.

Figured I will eventually beat the odds and actually get them ....

Mark.


----------



## wvgca (Jan 21, 2013)

Shipping from China has been poor for me as well .. Last few items that came in were ordered the middle of December, and the packages were marked air freight ..
who knows?


----------



## Mark R. (Jan 26, 2013)

I always figure, one - the package is never shipped with tracking, so the seller has no argument that I didn't receive it, and two - Paypal will always give me my money back if I file a claim that I didn't receive it. Fortunately it's only hobby stuff that isn't imperative that I get it next week. Always something else to work on ....

Mark.


----------



## gunrunnerjohn (Nov 10, 2010)

I used to get reliable shipments from China, lately there has been a spate of non-deliveries. I've had to get refunds for a bunch of parts orders, it's getting to be a real PITA. I'm wondering what has changed in the last few months, this started happening around the middle of last year.


----------



## jlc41 (Feb 16, 2016)

Very interesting solutions to the noise issue. Got to like guy's with this kind of knowledge.:appl:


----------



## wvgca (Jan 21, 2013)

Mark ..
if all you need is one 4 bank SSR, I have spares and can mail you one??
I assume high level trigger?


----------



## Mark R. (Jan 26, 2013)

Thanks for the offer Warren. I have four on order from a different ebay China seller made on the 18th. Lets wait and see if they show up.

Mark.


----------



## Mark R. (Jan 26, 2013)

China has failed me once again. After five plus weeks, I again filed with Paypal and got my money back.

Wonder what has happened ? I used to get electronics parts from those China ebayers all the time with no problem, and pretty quick too ! Now, I'm lucky if the stuff even shows up !

Mark.


----------



## T-Man (May 16, 2008)

I have noticed some China sellers sell everything, These are the guys to avoid. It is obvious they are a middle man and the biggest hint is the waiting time. One order I had was over 6 weeks. They did state the long wait on their orders. So I go with suppliers that I have used before and specialize in electronic parts.


----------



## gunrunnerjohn (Nov 10, 2010)

I've noticed a higher incidence of orders failing to arrive from China lately, don't know what is happening. Even a couple of places I regularly buy from have had issues getting product to me.


----------



## Mark R. (Jan 26, 2013)

Funny, I checked the original ad I bought the relays from and it now indicates in red type - Does Not Ship To Canada ! 

Mark.


----------



## time warp (Apr 28, 2016)

Doh!:lol_hitting:


----------



## time warp (Apr 28, 2016)

Maybe it's time you checked out the Binford 3000 series relays. :laugh:


----------



## highvoltage (Apr 6, 2014)

Mark R. said:


> Funny, I checked the original ad I bought the relays from and it now indicates in red type - Does Not Ship To Canada !
> 
> Mark.


That's interesting, I wonder why they won't ship there?


----------

