Better Quality Switches?

C

CoggesRailway

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I use a lot of these in their various incarnations: http://www.maplin.co.uk/sub-miniature-toggle-switches-2341 although the body is sometime red plastic- they are ubiquitous so I would guess you all know what I mean.

I use them for lots of things and also for loco control as I do very simple slow running battery locos. I expect this sees them thrown more than a simple power on/off. And they are used by kids too.

I am now at the third failure and it is very frustrating. I have re soldered the connections but I am fairly sure its the switch itself- after all all of the other components solder joints are not failing and it is always one of the outs as opposed to the middle in of the DPDT throw that fails.

They are very cheap and I would happy to pay pounds as opposed to pence for something more robust and with a more positive throw. It needs to me small but more rugged.

Any recommendations or thoughts?
 
You have to be careful of how much heat you apply when soldering, too much and you have kn***erd the switch
 
well I am certainly an amateur with soldering. would too much heat cause a failure after six months use? I guess it could cause the contacts to be more fragile.

Also Whatlep did a very neat job on soldering one of the offending switches and he is pretty handy?
 
CoggesRailway said:
I use a lot of these in their various incarnations: http://www.maplin.co.uk/sub-miniature-toggle-switches-2341 although the body is sometime red plastic- they are ubiquitous so I would guess you all know what I mean.

I use them for lots of things and also for loco control as I do very simple slow running battery locos. I expect this sees them thrown more than a simple power on/off. And they are used by kids too.

I am now at the third failure and it is very frustrating. I have re soldered the connections but I am fairly sure its the switch itself- after all all of the other components solder joints are not failing and it is always one of the outs as opposed to the middle in of the DPDT throw that fails.

They are very cheap and I would happy to pay pounds as opposed to pence for something more robust and with a more positive throw. It needs to me small but more rugged.

Any recommendations or thoughts?
Click to expand...

We had litterally hundreds of these in 6 large controll panels made up and fitted in house by our own electricians.

Similar results to you, within 6months (of robust use) = 75% failure rate,
two of the lads got so fed up of replacing them a few at a time they came in one Sunday (without pay) and changed the lot over to some from RS Components
http://uk.rs-online.com/web/c/?sra=oss&searchTerm=sub+minature+switches&x=26&y=18
They were still working fine (only 2 failures i can remember) over 18months later
when i left the team.

Might be worth a try next time you have to replace one :thinking:
 
I don't have any experience with either of the Maplin or RS switches, but I am concerned at the specifications.

Maplin claim 5A at 30V dc which is surprising since the 125V ac rating is only 5A. Usually a load breaking switch has a much lower (typically one tenth) rating on dc, compared to ac.

The RS switch has a rating of 0.05A

If you are opening the switch when it's is carrying current there is a high likelihood of early failure. An overloaded switch burns more contact material each time its operated and this causes early failure. That's different to the normal load current which causes heating in the switch. Overheating due to overload will also lead to failure. Switching 'on' an excessive load can also lead to failure, usually welding the contacts together, but that is less likely in a typical loco arrangement.

This probably does not help you find a solution, but I'm not certain what electrical load you are trying to switch. That depends on your loco voltage and how heavy your trains are. And don't try switching when going uphill!

I'm guessing that you should be looking at a switch with a minimum 1A dc breaking capacity at 24V with an expected life in excess of 100,000 operations. Neither of the switches meets that specification.

If you can give a bit more detail such as nominal battery voltage and type of motor (or just motor block details) then that would help. As would a circuit diagram, but that's not essential.

Regards, Don
 
I watch this thread with interest as I too am looking for a switch, I thougfht they were all the same, What a dummy I am!
 
When looking for those sub-miniature toggle switches i went into Maplin and flicked them back/forth. Some where much smoother in operation than others
 
Interesting thoughts. I seemed to have a few failures of Maplins micro-toggles, so I changed to Expo Drills & Tools. Now I am the most hamfisted guy when it comes to soldering. Some of my brass kit and scratch building in the double-oh days was hilarious. At times I felt I'd be better starting off with a block of lead and filing it down to the correct profile rather than soldering bits together.
So I am not casting aspersions on the quality of Maplin v anyone else. It's just that in my hands the Expo switches seemed to fare better. As has been suggested, too much heat was probably the problem (I have to say the guy at Expo is very helpful and the service is good).
 
With regard to the heat question, I have taken to using 145 degree solder, not because of its lower melting point (resin cored solder is 220 degrees) but because of the better flow characteristics of solder when using separate liquid flux.

This type of solder is usually sold as being suitable for brass kits :thumbup::thumbup:
 
Switches are a matter of interest in model-railroading.

I think what we have to take care about is the power that such a switch should handle with.
In HO-Scale a moderate loco with lights takes 1 Ampere or even a bit more.
I tried 1A-Controlers on my RC-Locos. too, and failed one by one. G-Scale-locos will take about 1Ameper when running light, but when the track becomes steep or curvy and u have heavy loads, there you will have very quickly 4-5 Amperes with a simple, small loco.

The problem with electricity is, that the energy we can use is a product of voltage and current. Volts * Amperes = Watts.
And for moving a heavy train, u have to have Watts.
Because of the missing voltage, there is no other way to use high current. And therefore the cheapest switches on market may be not good enough, no matter what the data tells.
Very cheap switches are often cheap because of the minor use of copper on the contacts.
The golden rule of switchmaking is: to make a copper-contact more durable, there is only one way: use MORE copper.

So a 5 A switch of thze cheap ones MAY be at technical borders.........
I am wondering a bit, because those switches often just take 2 A, 5 A is high on that price.......

As far as i know i have 5A switches in my locos, too, switching a 3 motored shay on high grade and heavy load....i never had any problems.
Using the lever-switches with the blue body offered by conrad. Not the red ones, they are low-cost.


Greetings

Frank
 
If a switch is rated 5A@125VAC/30VDC the 30Vdc rating is purely resistive.
Rerate for various loads as follows at 30VDC
Resistive x1
Inductive x0.5
Lamp x0.25
Motor x0.33
Capacitive x0.25

For 12VDC rerate as follows.
Resistive x1.25
Inductive x1
Lamp x0.31
Motor x0.41
Capacitive x0.31

One other thing to consider if you use silver plated contacts at very low currents is the tarnishing of the contacts.
Because very low currents don't arc the silver oxide off the contact you will eventually have an open circuit.
In this case make sure you use gold plated contacts.
 
don9GLC said:
I don't have any experience with either of the Maplin or RS switches, but I am concerned at the specifications.

Maplin claim 5A at 30V dc which is surprising since the 125V ac rating is only 5A. Usually a load breaking switch has a much lower (typically one tenth) rating on dc, compared to ac.

The RS switch has a rating of 0.05A

If you are opening the switch when it's is carrying current there is a high likelihood of early failure. An overloaded switch burns more contact material each time its operated and this causes early failure. That's different to the normal load current which causes heating in the switch. Overheating due to overload will also lead to failure. Switching 'on' an excessive load can also lead to failure, usually welding the contacts together, but that is less likely in a typical loco arrangement.

This probably does not help you find a solution, but I'm not certain what electrical load you are trying to switch. That depends on your loco voltage and how heavy your trains are. And don't try switching when going uphill!

I'm guessing that you should be looking at a switch with a minimum 1A dc breaking capacity at 24V with an expected life in excess of 100,000 operations. Neither of the switches meets that specification.

If you can give a bit more detail such as nominal battery voltage and type of motor (or just motor block details) then that would help. As would a circuit diagram, but that's not essential.

Regards, Don
Click to expand...

Don, are we not always opening a switch when it is carrying current?
 
Well this forum continues to be fantastic. I asked a simple question and got a lot of info as well as a surprising number of people with the same experience. Many thanks.

ian
 
Rhinochugger said:
With regard to the heat question, I have taken to using 145 degree solder, not because of its lower melting point (resin cored solder is 220 degrees) but because of the better flow characteristics of solder when using separate liquid flux.

This type of solder is usually sold as being suitable for brass kits :thumbup::thumbup:
Click to expand...

I always though it was inadvisable to use a liquid flux on electrical soldering, due mainly to it remaining active after it has cooled. Resin flux doesn't.
 
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