Motorcycle Intercom Push To Talk Button

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cheeseslice

Member
Hi,

I'm currently installing a new intercom system onto my motorbike and I have got to the stage where I am building the push to talk button and bracket for the handle bar.

The button will be a push to make and will run back to the picaxe which will be hidden away under the seat. I will hopefully be making a bracket similar to the one in the picture I have attached.

My question is basically whether or not I need this button to be waterproof or not. I was planning on just buying a large push switch from maplin and using a normal heat shrink to seal it up.

Would it matter if any water got into the switch? If so, would anyone know a good way to solve this?

I was trying to find a really small project box that I use but I can't seem to see any small enough.

Cheers
 

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Andrew Cowan

Senior Member
I was going to post that it wouldn't need to be waterproof, as you are only talking a few drops of rain, plus the current/voltage will be low. Heatshrink, silicon sealant, etc...

However, if this is connected to the motorbike battery (or anything motorbike related), I'd say to go with a proper waterproof switch.

At PICAXE currents and voltages, the only problem is rust, which would then stop the circuit working.

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cheeseslice

Member
Andrew Cowan said:
I was going to post that it wouldn't need to be waterproof, as you are only talking a few drops of rain, plus the current/voltage will be low. Heatshrink, silicon sealant, etc...

However, if this is connected to the motorbike battery (or anything motorbike related), I'd say to go with a proper waterproof switch.

At PICAXE currents and voltages, the only problem is rust, which would then stop the circuit working.

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Click to expand...
The switch will be connected to a picaxe which is being used to switch between different transmitting modes, it will then be connected to an autocom intercom system which is connected to the bike electrics.

The picture that I attached is a bracket and switch that you can buy but they want around £45 for the bracket, button and a 3ft cable with a 5 din connector at the end. It looks like they have just used heat shrink but then it's hard to tell from just looking at the picture.

With the waterproof/splashproof buttons that I have found they all look like they will have to be mounted in a box which is something I was hoping to avoid.

http://www.maplin.co.uk/searchtemplate.asp?criteria=WATERPROOF PUSH SWITCH
 
hippy

hippy

Ex-Staff (retired)
I'd probably go with the switch as is. Heat shrink over the switch solder tags, then larger heat shrink to wrap the cable and body ( or the standard greasy biker's, "yard and a half of insulting tape" [sic] ).

Make sure the switch is PTM active low, one side to 0V the other to PICAXE pin with a 10K pull-up to +V. Should be pretty safe even if it does short-out the instant it rains. Probably worth putting a 1K in series with the pin ( after 10K pull-up ) for a bit of ESD protection.
 
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Andrew Cowan

Senior Member
I don't think water and shorting are the problem.

I've run motors underwater without any problem, except that the next day they are completly rusted up.

My tap water has a resistance of 100K/mm. Not enough to casue any problem under 10V.

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cheeseslice

Member
Andrew Cowan said:
I don't think water and shorting are the problem.

I've run motors underwater without any problem, except that the next day they are completly rusted up.

My tap water has a resistance of 100K/mm. Not enough to casue any problem under 10V.

A
Click to expand...

So do you think putting this switch:

http://www.maplin.co.uk/Module.aspx?ModuleNo=34858

on a bracket, maybe putting a bit of silicon/glue (or something better?) on the connectors once they are soldered and then heat shrinking the entire back of the switch would be enough?

I was just going to use cat 5 cable that I have lying about to run back to under the seat.
 
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Wrenow

Senior Member
1) For waterproofing the connections, use 3M Scotchkote (available at Lowe's in the electrical section, not carried by Home Depot in the US - not sure who the UK sources are). Liquid electrical tape silicone glue, etc. tend to delaminate over time, allow moisture in, and then hold it there to enhance corrosion. Same with shrinkwrap, if you do not Scotchkote it first.

2) For keeping the switching contacts fresh, you might try spraying some Corrosion-X into the switch or go with a Marine rated switch (you local boat store or marine supply should have marine rated switches).

3) Cat 5 cable, if the single strand variety, may be a really bad idea. I believe that vibration and flex will cause an intermittent failure over time in your application. You probably want a high strand count wire with a silicone or teflon insulator.

Seems a picaxe may be a case of having a hammer making the problem look like a nail. Would it not be pretty much as simple (or simpler / cheaper / more trouble-free) to just use a simple relay to switch modes? Or, if you want to change and hold mode changes, a step relay?

Cheers,

Wreno
 
hippy

hippy

Ex-Staff (retired)
There are two corrosion issues; solder tags and water ingress to the internal contacts.

Probably best to try it for the silicon and heat shrink. Cut a piece of wire, solder it back together, wrap, leave in a salt water and vinegar solution for a while. See what that does. Unless someone's tried it they simply be guessing if it would work.

To prevent ingress you really should buy an IP rated switch.

Cat 5 has eight cores and is chunky which is a pain. I'd buy a yard of two-core bell cable or find a length of Christmas light cable which is stated as usable out doors. I've never had any noticeable problems using two-core mains cable in the rain and snow or in the car engine compartment. You may have a figure-eight mains lead knocking around which is usable.
 
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cheeseslice

Member
Wrenow said:
1)

Seems a picaxe may be a case of having a hammer making the problem look like a nail. Would it not be pretty much as simple (or simpler / cheaper / more trouble-free) to just use a simple relay to switch modes? Or, if you want to change and hold mode changes, a step relay?

Cheers,

Wreno
Click to expand...
You are right and and I'm in two minds at the minute. I had thought about using the picaxe so that I could maybe put a rotary switch on the handle bar too, then build an interface to the radio and use this to change the channels if I needed but the more I think about it the more inclined I am to just run two core straight up to the switch.

I need to get this all done within the next 2 weeks and I don't have a lot of time at the minute so the simple solution might just be the best.

I have never had to look for a waterproof switch before, they are quite expensive!
 
hippy

hippy

Ex-Staff (retired)
Expense is all relative. A major factor is lifetime, it's a ready to go solution, guaranteed to be what its says on the "IP" label.

Cable rotting I wouldn't worry about. If it does fail early it's relatively easy to replace.

That leaves solder tag corrosion. If you can find an IP switch with flying leads then you can solder to those, then if it does corrode cut back the bad and still have a workable length of lead.

As it's not a critical component it's probably good enough to choose anything, replace it later if any problems do show up. If you don't wash the bike then all the accumulated greasy crud may give it an extra degree of water-proofing :)
 
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