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Author Topic: To switch or not to switch that is the question....  (Read 2587 times)

John W E

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To switch or not to switch that is the question....
« on: July 04, 2007, 06:25:16 PM »

This topic yet again is aimed at those who wish to have a go at building their own electronic kits.   This will follow the same format as the last topic, where I am not setting out what is the best kit and what is not and what are the best tools for the job and what are not.

To start off, the switcher kit I have built this time is a P62 'Quadswitch' 4 x latching relay switcher.

I will leave all the pros and cons until right at the end of this topic; also, any comments about tools used or methods used.

So right, straight into it

Tools we need - same as before, very basic tools - which are here; toothbrush (an old one  ;D) a small terminal screw driver, long nosed tweezers, long nosed pliers, side cutters, magnifying glass, granny hair clip, two croc clips for heat sinks and a meter which is very helpful (not critical, but, in this kit build it does help you at the later stage).

What do we get in the kit:-

We get an IC chip, 4 transistors, 4 diodes, 3 zero ohm resisters (jump wires to you and I), capacitor - its an electrolytic capacitor.  We also get 4 relay coils, 4 three way screw connecting blocks, and a plastic case.  Plus we also get the IC socket.

We also get a good set of instructions for how to build the kit, Very easy - plus we also have a good drawing of the assembly, with hints and tips on soldering.
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John W E

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Re: To switch or not to switch that is the question....
« Reply #1 on: July 04, 2007, 06:33:47 PM »

Now we have the kit and the tools - lets make a start:

Okay - so we start off with a PC board, and the first item we solder in is the IC socket.   This socket has a notch in it which has got to go the correct way.  As before if you drop a clanger and solder it the wrong way, dont panic, but, a word of advice - study the drawing of the PC board so you know exactly which way it goes.   Once we have soldered this in place, I used me granny clip to keep the socket flat to the board.

Now we solder in the links L1, L2 and L3.   We have used these before in our builds.  They look like a resistor but they have a black band around and it doesnt matter which way these are soldered into the PC Board.

Now we move on to a new component, this is called an Electrolytic Capacitor.   It is critical the way these are mounted.   You will notice that on the side there is a strip, which indicates the negative leg of the capacitor.
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John W E

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Re: To switch or not to switch that is the question....
« Reply #2 on: July 04, 2007, 06:46:43 PM »

Now comes another new component on our list - diodes - it is again critical which way they are mounted on the board.  They look like a glass bead with a black ring around one end.  The way they are mounted on the PC board, they are mounted vertcally with the black identification ring the furthest away from the PC board.  Care has to be taken with these, although they are pretty robust, too much heat will crack the glass on them.

Now we have mounted 4 of these.

We now move on to mounting the screw connection blocks, and the only thing which I will say about these is something that is mentioned in the instructions MAKE SURE YOU DO MOUNT THEM SO THAT THE CONNECTION HOLES FOR THE WIRES FACE THE OUTSIDE EDGE OF THE PC

Once we have soldered in place the connection blocks, we now solder in a three-pin plug.
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John W E

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Re: To switch or not to switch that is the question....
« Reply #3 on: July 04, 2007, 06:53:24 PM »

Now we come to the delicate part.   This is where we need our aluminium cooking foil/sheet of aluminium.  Because, we are going to use some static sensitive components here.     Place your aluminium sheet on the bench, along with your 4 transistors and your IC.  Also your PC board which you are building.   

Place your hand on the aluminium along with your soldering iron.   Make sure your soldering iron is well away from the components and your hands.   This will discharge any static build up.   Now we have to solder in the 4 transistors.  This is where I used the crocodile clip as a heat sink between the transistor and the PC board, whilst I soldered it.   Try and make these soldering joints as quickly as possible.  Once these have all been soldered in, ensure you have them soldered in the correct way - have a look at the top of the transistor.  You will see that there are two chamfered edges - make sure these correspondend with the drawing.
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John W E

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Re: To switch or not to switch that is the question....
« Reply #4 on: July 04, 2007, 06:58:31 PM »

Next I made the receiver lead and soldered this into the PC board.   I made this up from cable which I purchased from Model Power to suit my Futaba set up, along with sockets and plug.

The next stage is the simple insertion of the IC into the socket, ensure you have the notch in the right way, remember if you dropped a clanger and soldered the socket round the wrong way the notch will be at the opposite end.  Now we have to turn the PC board over and examine for any dry joints or any splashed of solder between the tracks.  We now then clean the back of the board with a toothbrush and some methylated spirit.


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John W E

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Re: To switch or not to switch that is the question....
« Reply #5 on: July 04, 2007, 07:16:30 PM »

Now the set up and testing....

This is where the multimeter comes in very handy.  However, if you dont have one, a 6volt bulb plus a 6 volt battery and some wire would suffice.

First of all, we need to connect up our switcher to our RX.  Any channel, apart from the throttle channel.   I used the rudder channel for the set up - number one.  I switched my transmitter on first and then switched the power on to my RX.

Then, I connected up the probe from the multimeter to the outlet on switch one.   My multimeter was connected across the terminals of switch one - one side common and one side normally closed.

I moved the transmitter stick full over to the left, until I heard the relay click.   This indicated that the relay had switched.  This was shown on the meter.

I then moved the stick on the transmitter in the opposite direction which re-energised the relay switching it back on.

Now with this set up, on this switcher please remember you have to move the stick on your transmitter from centre to its extreme once & back to the centre.  This switches number one relay on. 

Do it twice and this switches relay number two on. 

Do it three times and this switches number three on.

Do it four times and this switches number four on.

Now - if we move the stick in the opposite direction the same amount of times, it de-energises the relays in turn.  4,3,2,1

It takes some time to understand the operation of this switcher and also the movement on your controls.

But, once you have mastered them and understand them it becomes fairly straight forward - its a case of the man has to get used to the electronics set up and not the electronics getting used to the man ;D

Once you are satisfied with the operation, we move on to the last stage and that is fitting it into the box.   It is honestly just a case of drilling 12 holes or 2 large slots if you prefer in either end of the casing to facilitate your cables or your wires plus a hole in the side to facilitate your RX lead.
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John W E

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Re: To switch or not to switch that is the question....
« Reply #6 on: July 04, 2007, 07:22:50 PM »

Hope you have enjoyed the build.    I hope this inspires a few people to have a go at a kit.  The actual build of this kit was very easy/straighforward.  Although, I will admit to dropping one clanger!! I had a dry solder joint on one of the legs on the IC and it took me a good hour/hour and a half to locate and remedy my own clanger!  :P

What I would suggest is anyone who builds the kit and feels there is a problem to go over all of their soldered joints, just as I did - maybe 2-3 times to ensure its right.

The longest part was the set up and understanding the operation of this switcher unit. 

What I havent mentioned, is it has the facility to be used on a two-channelled radio.   The socket that you solder in on the PC board is for your rudder servo.   I wont go into the details of this just now, because I want to set this up on a two channel radio and see how it operates.

Hope you have enjoyed this  ;D  The kit only took about 2 - 2.5 hours to build that was with taking the photographs set up etc., plus a further few hours to sort out my own clanger NOBODY PERFECT

Aye
John E
Bluebird
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Tom Eccles

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Re: To switch or not to switch that is the question....
« Reply #7 on: July 05, 2007, 07:32:39 PM »

John,

Again a very informative thread.

I am not sure what makes me happier, having Dave at ACTion being so helpful or you showing an idiot like me just how electronics/electrics can be made to work.

I have the electrical expertise of a whelk and welcome any and all threads like this.

Tom

P.S. how about a master class on things that you experts may think everyone knows (and many will be too ashamed to ask) such as how to decide what amperage of cable to use in a given application, and what is the best size of battery for differing sizes of motors??

Please keep up the guidance
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John W E

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Re: To switch or not to switch that is the question....
« Reply #8 on: July 06, 2007, 10:23:31 PM »

hi all

This is a footnote to go with the switcher.

The switcher was obviously designed with the operator only having 2 channels, ah the good old days.  It has a facility built into it, where you plug your rudder servo into it.   What happens when you use your rudder stick on the transmitter as per normal you have a slight delay in the response of about half a second in the rudder movement.

However, if you are to flick quickly to full rudder movement to say port and then back to centre, you operate the switcher and this would bring in relay one of the switcher unit,   If you flick in the same direction twice quickly to the extreme and then back to the centre of your rudder stick, this brings in number 2 relay and soforth, which I think is personally excellent for those who have only two channels.

Hopefully, my quick sketch shows you what what I intend to do with the switcher unit that I have built.  That is to drive the sound unit, navigation lights, plus smoke generator, plus a search light. 

This switcher unit has its limitations that the relays will only handle one amp.   You can get a 2 channel switcher unit, which will handle a greater amperage, for those who wish to operate water pumps for fire monitors possibly winches etc. and items like bow thrusters which normally operate around about 2-3 amps at short term. 

Those with greater electronic experience could no doubt upgrade the relays to handle greater amperage.   However, for us, as beginners I dont think we really want to go into that field yet.

Hope this explains a bit of what this switcher is capable of doing and explains more of what it does  ::)

aye
John e
bluebird
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Roger in France

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Re: To switch or not to switch that is the question....
« Reply #9 on: July 07, 2007, 10:31:01 AM »

Very interesting and helpful, thanks.

I would like to take a slight side track from the "...building a switch theme...." and ask as follows.

I recently saw someone mention that he operated his main power on/off switch - in the model - from his Tx.  The only advantage I can see for such an arrangement is that one does not therefore need a switch mounted on the superstructure or accessible when the model is assembled. On the other hand a channel is dedicated to that sole purpose.

What are the pros and cons for such an arrangement?

Roger in France.
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funtimefrankie

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Re: To switch or not to switch that is the question....
« Reply #10 on: July 07, 2007, 02:07:18 PM »

But surely, once switched off you cann't switch it on again, by radio? 
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John W E

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Re: To switch or not to switch that is the question....
« Reply #11 on: July 07, 2007, 09:16:48 PM »

Hi there Roger in France

This question you ask about shutting the main power off via the radio - I cant honestly see an advantage or the only advantage I could see would be in the case of an emergency i.e. someone on the same frequency causing interference - you would be able to shut down your main supply to your motors, bringing the model to a standstill.   However, you would be in serious trouble if you are running BEC because that would shut all your electrics down completely.   You wouldnt be able to re-engerise them, unless you brought it alongside.  Whereas you would have to manually switch the unit back on somehow.

To be honest with you, I cant see any advantage of that - maybe someone else could enlighten us  ;D

Aye
john e
bluebird
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Roger in France

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Re: To switch or not to switch that is the question....
« Reply #12 on: July 08, 2007, 09:42:44 AM »

Exactly what I thought. OK for an absolute emergency but for little else.

I guess that if you had your radio on a separate supply you could switch main power on again. However, I see no great advantage with such a system and was wondering if I had missed something obvious.

Roger in France (currently visiting the UK!).
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FullLeatherJacket

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Re: To switch or not to switch that is the question....
« Reply #13 on: July 09, 2007, 05:32:31 PM »

As Bluebird says, you'd have to have a separate battery pack for your receiver or FunTimeFrankie's comment is absolutely spot on! Sometimes a little philosophy comes in handy, doesn't it? You would also need a fairly hefty relay in the switcher or a couple of heavy-duty power FETs to handle the main power current. Can't really see the point to it meself, but what do I know?
Incidentally, John mentioned earlier in the thread about higher-rated relays being available in the ACTion twin switch. True - but they aren't available in that pin-out any more and I only have about 18 left. So if you want a 3A twin-switch then you'll have to be REALLY nice to me!
FLJ
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