Can a crest 5475 be made to actuate solenoids ?

maxi-model

maxi-model

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I chose an off the shelf latching relay to keep it simple as I had the impression that Max wanted simple.............
Well that part of your post I understood Greg :) The rest, well......... The problem for me is I do not understand electrical schematics, let alone any terminology surrounding them. By "plug & play" I meant just that. It either does what it says on the tin or it doesn't. How it does it I probably don't have a clue, but I'll try. To quote Arthur C Clarke - "Any sufficiently advanced technology is indistinguishable from magic". I'm at the stage where whatever the solution is it will probably fit that quote to my eyes and feeble mind :D

However, gentlemen (and any ladies) please carry on your deliberations as it seems as though we might be coming close to finding a finite answer to my original question. Whether is be positive or negative (at least I understand that part of electrickery) Max
 
The Tinker

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Greg can you please enlighten me as to where I would need to put the diodes and how I might wire these units in to my Crest 5475 unit As they may be a good solution for me, to run my 5 air solenoids
 
Greg Elmassian

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John now gets my idea... he found the correct type of latching relay, and given the proper one is purchased (right coil voltage), it is as simple as his drawing. I was a bit too busy to look up the right part, I found the 2 coil units... and let John explain his circuit, I did ask questions, but I think completely moot, as I would us the simpler suggestion I proposed first.

The diodes, called "snubber diodes" among other names (flyback diode) go across the solenoid coil, in the reverse direction of the normal current flow.


See figure 3... and it would be good to read the article.

Basically, when ANY coil operated on DC (motor, relay, solenoid) has it's power interrupted or turned off, a current flows from the collapsing magnetic field. It runs in the opposite direction to the current created it... This is BEMF, Back (reverse) Electro Motive Force (voltage)


Greg
 
Greg Elmassian

Greg Elmassian

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John now gets my idea... he found the correct type of latching relay, and given the proper one is purchased (right coil voltage), it is as simple as his drawing. I was a bit too busy to look up the right part, I found the 2 coil units... and let John explain his circuit, I did ask questions, but I think completely moot, as I would us the simpler suggestion I proposed first.

The diodes, called "snubber diodes" among other names (flyback diode) go across the solenoid coil, in the reverse direction of the normal current flow.


See figure 3... and it would be good to read the article.

Basically, when ANY coil operated on DC (motor, relay, solenoid) has it's power interrupted or turned off, a current flows from the collapsing magnetic field. It runs in the opposite direction to the current created it... This is BEMF, Back (reverse) Electro Motive Force (voltage)


Greg
 
John S

John S

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Greg, how you visualised the setup?.................

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AlanL

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John, have you made a mistake with your diagram above? When the top output of SW A is positive, the positive flows through the top diode but after the relay coil it is blocked by the lower diode (black) or goes to the lower output SW A (red). Etc.
If the output from SW A is reversing, a single coil relay will not permit 2 diodes across the coil, they will block current in both polarities.
Perhaps a better solution is a two coil latching relay with a diode across each coil ?
Alan
 
John S

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I did ponder and wonder about the diode orientation with regard to the feedback from the coil, including using two pairs on each of the output lines, with one of each pair reversed, will have a check with a breadboard setup with a couple of diodes, will have to re jig the PIKO switch decoder to operate as momentary with reverse polarity.

Whilst pondering, came across a reference to using something called a "C Circuit", using a non polarity capacitor across the coil of single coil latched relay.

The scenario is for a Simple circuit to use the 5475 outputs that are momentary and have polarity reversal.

Have some components on order, will tinker with the circuit from post#17, plus coupled with the ongoing development work for Air Solenoid Valves operated by DCC, plus some experimentation with off the shelf Radio Control, along with a collection of Home Brew DIY circuits for DCC, Bluetooth, and WiFi, something useful and constructive may even materialise from the tinkering.



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maxi-model

maxi-model

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John, would it help if I were to provide you with a 5475 RX bound to a 5473 TX on Ch1 with their operating instructions ? Or is what you are working on intended as a "generic" solution. I have just acquired the TX as a spare, and an RX controller too. They have been tested and appear to function as they should. In fact they appear virtually unused and fresh out of the box, so to speak. Max
 
John S

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Max, that's an excellent suggestion, could try out various ideas and alternatives, aware that others here on the Forum are looking for alternative methods of control, and would indeed reduce the need for some of the educated guesswork.

I'll drop you a PM with my address, will also increase my component order for various bits and pieces, perhaps with a fair wind may be able show any interested individuals some practicable work arounds, at the forthcoming Exeter Garden Railway Show in late October.
 
Greg Elmassian

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The diagram has wires to nowhere....

The relay sets in one polarity, and resets in the other, the Switch "A" wires should go directly to pins 1 and 10.... the diodes I referred to the first time were for your JK flip flop circuit.

The second time I referred to the diode, it was across the air solenoid, not in your last diagram, but it is the diode on the far right in your diagram in post 26.

To sum up: 2 output wires for a switch go directly to pins 1 and 10, positive power to the solenoid (usually 12v or 24v) goes to pin3, and the "negative side" of the diode on the right and one side of the solenoid.

Pin 4 feeds the positive side of the snubber/flywheel diode and the other side of the solenoid.

the pneumatic solenoid is on if power is applied and off if no power.

no need to use the second set of contacts or the redundant connections to switch A outputs.

the 5472 had 3 momentary with apparently 2 that have the polarity reversing for switching and 2 latching just on off..
The 5474 had 2 momentary for switch machines with polarity reversing, 1 on off with about 100 ma capacity and 2 that were optoisolators good for maybe 10 ma
The 5475 had 5 outputs for switch machines, with polarity reversing, all momentary.

So since the question was on a 5475, this would be the best unit to use, get 5 latching relays as above, and 5 1n4001 diodes and 5 pneumatic solenoids and you can control 5 switches... I don't know how this got so confusing.

Maybe correct the drawing including my changes and the pneumatic solenoid?

Greg
 
John S

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" The 5475 has 5 outputs for switch machines, with polarity reversing, all momentary.

To sum up: 2 output wires for a switch go directly to pins 1 and 10, positive power to the solenoid (usually 12V or 24V) goes to Pin 3, and the "negative side" of the diode on the right and one side of the solenoid.

Pin 4 feeds the positive side of the snubber/flywheel diode and the other side of the solenoid.


The pneumatic solenoid is on if power is applied and off if no power.

So since the question was on a 5475, this would be the best unit to use, get 5 latching relays as above, and 5 1N4001 diodes and 5 pneumatic solenoids and you can control 5 switches... I don't know how this got so confusing. "


Actually there appears to be no confusion, what does manifest itself is the lack of any diodes to prevent "flyback" from the relay coil to protect the 5475 switch outputs?

As to whether to apply the Negative power via the relay contacts 8 & 7, is nit picking to say the least!

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Going back to post#17, the 5475 outputs are "isolated" and therefore protected.

In simple terms, when switch A is pressed and activates SW A, the Bridge Rectifier ensures polarity is always Positive, turns the optocoupler LED on, the transistor then conducts, which provides a signal to the CLK input, which then sets the "JK" type "flip flop", and turns the "Q" output on, it stays "ON" in this configuration, "UNTIL" another pulse is seen on the CLK input, which is provided by another press of the A key to activate the 5475 SW A output, and now the "JK" "flip flop" changes state and turns "OFF" output "Q".................

The truth table as provided, illustrates the states of the "inputs" and "outputs", output "Q" can be toggled ON or OFF.................


Referring back to AlanL post #27...went and checked diode orientation using a PIKO switch decoder, my humming and aaaing about the diagram in post#26, and musings in post #28, also included a 104 decoupling capacitor for use across the 5475 outputs, relays are notoriously noisy in the electrical sense, not sure how the 5475 would react to excessive electrical noise on it's internal circuitry.

All in all, still a very Simple Circuit, proof of the pudding so speak, will be to try it and see, those particular relays referenced to for use, are proving to be somewhat elusive to find on this side of the pond, will try another search for them...........

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maxi-model

maxi-model

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There might be a big fly in my ointment here John. Just went to bind my recently acquired ("unused") 5475 to my recently acquired (different source) spare TX and it seems the 5475 does not appear to be able to receive any signal from either it or my other, well used, TX to bind it to either of them.

I powered the 5475 up, red power LED on, Crest @ 13.8v DC as power source. I pressed an "Alpha"(eventually any, not just A) key on the TX, as per the instructions, and at the same time the "code set" button" on the 5475 - no flashing, or even steady green, LED signal light lit on the 5475. I tried both my transmitters, that I know are functioning perfectly with their respective 5471 RX's. Tried using different channels on each TX, still no luck. The green "signal" LED on the 5475 just will not light up. Not a flicker.

Yes, no other receiver was switched on when carrying out the binding process. And, as I am aware this can be an issue with the speed controlling RX's (though not mentioned in the 5475's manual) I have kept the TX and RX's as far apart as possible (arms width, I'm 6' tall) when carrying out the binding process. The aerial lead is not detached from the board, I opened it up to check. Everything looks clean and pristine as though the 5475 is fresh out of the box.

The Ebay listing for this item stated "never used" & "fully working". Interesting, if "fully working" how come none of the 10 channels on either of my TX's will cause the green "signal" light on the 5475 to illuminate when Button A is pressed on the TX. Is there some way a previous binding operation can be deleted without leaving any trace of this being done to allow the claim "fully working" to stand as true.

So, do I have a faulty 5475 or am I making a very basic mistake. Remember it is "Plug & Play" Max you are dealing with here :D
 
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John S

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Max, unfortunately "Plug & Play" is not my strong point! Bag of components and bits of wire...........:)

No doubt someone will pop along in due course and offer advice, meanwhile I'll continue to hunt down the elusive relay...:mad:
 
John S

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Kemet EA2 relays, hmm!, methinks a rethink for the Simple Circuit...............:rolleyes:

Digi-Key...
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And from Mouser.............

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Greg Elmassian

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Ohmigod... so the first drawing in post #32 is correct, except I would like to see the pneumatic solenoid connected.



Although the waveform is misleading, why put what most people would assume is AC there? the outputs from SWA are momentary, and the polarity is set by the button you push...

These momentary pulses from the Crest will either set and latch the unit in in one of 2 states depending on the polarity... set or reset.

When "set" 12 volts will be supplied to the pneumatic solenoid connected to the red and black wires at the right.

The solenoid is NOT polarity sensitive. When the power is turned off, the back emf from the solenoid is absorbed by the snubber/flyback diode.

That works.... follow that schematic, it is the simplest ... also there are tons of manufacturers of these latching relays and more suppliers than just Digikey.

BUT:
The circuit below does NOTHING, since the addition of the 2 diodes connected to the SWA outputs blocks EVERYTHING.... plus the errant picture of a noise capacitor that the text says is connected across the SWA outputs is probably not needed. The inductance of the latching relay coil is most likely so minimal that there is no need, but it would not hurt, just take out those dang diodes!!! Any diode on the output of SWA will block one of the polarities, and 2 in this configuration block everything.


 
John S

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BUT:The circuit does NOTHING, since the addition of the 2 diodes connected to the SWA outputs blocks EVERYTHING.... plus the errant picture of a noise capacitor that the text says is connected across the SWA outputs is probably not needed. The inductance of the latching relay coil is most likely so minimal that there is no need, but it would not hurt, just take out those dang diodes!!! Any diode on the output of SWA will block one of the polarities, and 2 in this configuration block everything.
132924_be734084ad6729ec7a264f9bed697671.png


BUT:The circuit does NOTHING, since the addition of the 2 diodes connected to the SWA outputs blocks EVERYTHING.... plus the errant picture of a noise capacitor that the text says is connected across the SWA outputs is probably not needed. The inductance of the latching relay coil is most likely so minimal that there is no need, but it would not hurt, just take out those dang diodes!!! Any diode on the output of SWA will block one of the polarities, and 2 in this configuration block everything.
132926_ec386ec6a2c455fc0c0173da3cbc9b42.png


BUT:The circuit does NOTHING, since the addition of the 2 diodes connected to the SWA outputs blocks EVERYTHING.... plus the errant picture of a noise capacitor that the text says is connected across the SWA outputs is probably not needed. The inductance of the latching relay coil is most likely so minimal that there is no need, but it would not hurt, just take out those dang diodes!!! Any diode on the output of SWA will block one of the polarities, and 2 in this configuration block everything.
132928_8e896a302b4cb29234cc63873e393315.png



Me, I'm not saying a word! :D

Well a few sentences perhaps, anyone want to connect a Relay to a DCC Switch Decoder or a 5475 without a diode or (diodes) to prevent flyback, and report back on the outcome?

NOTE: That is not a serious question, BUT perhaps the individual across the pond would like to connect his Digitrax Switch Decoder directly to the relay he is advocating, and let us know the outcome?, before suggesting that Max SHOULD connect a Relay to the outputs of the 5475 WITHOUT a diode or diodes?

Just to nip in the bud the usual waffle and procrastination, the PIKO switch decoder was reset back to default as supplied, momentary action and polarity reversal, acts and behaves exactly as the outputs on 5475, and for proactive testing, the switch decoder outputs were swapped over and like wise the Multi meter connections, result was the same, as the diodes were drawn and inserted in the circuit mentioned, Positive and Negative voltage will pass through from the outputs, therefore they are not blocked, likewise the reverse is also true, they will block any erroneous voltage spike generated by the Relay Coil from passing back to the outputs!


Going with Plan B, try and simplify and lower the component count as the idea in post#17, seems a pointless exercise trying to locate the Relay type as specified, spent far to many hours already, searching and reading data sheets, almost all so far fruitless, did find one at, £4.26 + £17.62 for taxes and import duties, + another £25.00 for p+p!

Note to the individual from across the pond, sarcasm is the lowest form of wit, the purpose(s) of this Forum, is to Inform, Educate and promote "best practise", any ideas or suggestions others make should be always be respected, corrected if needed with justifiable reason, but never derided, put down, contradicted, sneered at, or nit picked, based on conjecture, speculation or pie in the sky methodology!
 
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Greg Elmassian

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Your pictures do not match your schematic...

Notice the orientation of the 2 diodes in the schematic as opposed to your picture.

Start there... I will address your issues one by one, and we can clear them one by one.

So let's address my statement that the schematic below does nothing... look carefully... the answer is below the schematic.



You need to reverse one of your 1N5819 diodes in your schematic... no current can flow from SWA wires given this schematic.

Greg
 
John S

John S

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I've checked the pictures against the schematic, the diodes do match the orientation of the way the direction that voltage flows, a check with the multi meter confirms voltage is flowing from the source, which in this case are the outputs from the PIKO switch decoder.

The PIKO switch decoder, maybe with hindsight is perhaps not the best choice, only thing to hand to work with.

Have sat quietly and studied very carefully the schematic, direction of flow from the orientation of the diodes, and have worked through the various scenarios, and had a rethink about it, and made the necessary adjustments or corrections.

OK, after many deliberations and testing, should have payed more attention to my own gut reaction, the 104 Capacitor is required, the electrical noise generated by the relay when switching is horrendous.

Breadboard circuit used for testing, has been thoroughly checked, rechecked, tested and retested, with a LED, Relay, conventional Digital Multi Meter and a Scope Meter....

Debatable as to whether the Relay itself useful for switching a Solenoid Air valve, not only because of having to use both a Positive and Negative voltage to activate the Relay, no protection, can be afforded to the 5475 outputs to protect them from the resulting voltage spike that occurs when the coil of the Relay collapses either due to using the button to activate the Relay on or off, or an interruption to the power which causes the coil to collapse, and whether the Relay contacts are man enough to keep switching a Solenoid on and off

It a nutshell, and it's highly unlikely that the 5475 outputs have any form or at best a very mediocre protection, after all it was original designed for voltage to flow out from the 5475 outputs.

I'll wager the designers never expected that anyone would come up with an idea for a circuit for voltage to flow back into it.
From testing using a steady fixed voltage supply of 12V, and from the coil collapsing, voltage will shoot straight back into the inputs, probably destroying the whole unit in the blink of an eye.

Bottom Line..after all this, the Simple Circuit as suggested using a Relay...will require additional circuitry, Transistor, Resistor, Capacitor, and a Zenner Diode to provide the necessary protection to prevent "flyback" from the Relay Coil from damaging the 5475.

Plan B it is then............

Although, as with everything in life, from the circuit and subsequent schematics did discover a few useful tricks and ideas for the non conventional use of PIKO Switch Decoder outputs....

And, naturally I did learn something else, should have paid more attention and heeded the advice from my correspondents on the American Garden Railway Forums, now been put in place.......................
 
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John S

John S

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maxi-model maxi-model and the The Tinker The Tinker , have managed to source the relays, if it's OK with you two Gentlemen, I've gone ahead and ordered a few, to construct a working version, which I'm happy to send out to you for testing and see it will it serve the purpose to power an Air Solenoid.