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Replacing Switches (Caution! Nerdy)

MEXICOWANDERER
Explorer
Explorer
Not satisfied with being hip-deep in projects I am looking into replacing the lamp and water-pump switches in Quicksilver with membrane touch switches. They glow orange with about 1.5 ma current, and have touch buttons. Totally environmentally sealed.

But I need to fire NPN MOSFETS (TO247) and have been searching for something that does not live up to the moniker FET (Fire Emitting Transistor)

I ran across this possibility...

http://www.infineon.com/cms/en/product/power/power-mosfet/20v-650v-automotive-mosfet/20v-40v-n-chann...

Membrane slid-state switches would certainly eliminate issues with depth of switch body.

Rockers are not reliable and toggle switches are oogly.

The idea of running power directly to the lamp with only a micro breadboard and TO247 heatsink appeals to me. Micro-cable can connect the membrane switch.
21 REPLIES 21

MEXICOWANDERER
Explorer
Explorer
NERD CANDY!



Chris_Bryant
Explorer II
Explorer II
A bit more timkering, but you could also use this Intellitec 24 volt load controller- 6 switched loads, either switch per line, hi or low side, or multiplexed digital.
-- Chris Bryant

MEXICOWANDERER
Explorer
Explorer
Tis entirely indeed a issue of wet bulb (ugh) dry bulb (yay) corrosion.

Condensation precipitates salt out of solution. So if dew does not accumulate it can DO no damage. This is why I allow the bus to heat up during the day. Cruising sailboat owners thought I was nuts mounting alternator voltage regulators a foot distant from water cooled exhaust jackets. But diesels have a habit of emitting a fine oil vapor and plus the heat, it keeps terminal boards shiny. That and mounting the regulator like I did on Quicksilver, on a square 12" piece of 1/4" aluminum plate using silver heat sink mounting paste. The plate sucks heat from the regulator like you cannot believe.

pianotuna
Nomad III
Nomad III
Hi Mex,

I thought that heat would increase the rate of any chemical reaction and increase both corrosion and oxidation. ISTR that the rule of thumb is a doubling of the reaction for each 10 degree C (18 f) that the ambient temperature goes up.

Or is this some sort of dew point issue?
Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

MEXICOWANDERER
Explorer
Explorer
Well I am definitely going to purchase those flip-flop switches that Gordon Three so kindly posted. Eight of them as a matter of fact. By virtue of them being tucked in the ceiling they will store at a higher temp than shade ambient and hopefully lessen corrosion and oxidation.

I have those two streetlamps soaking in acetone at the moment. 300 pesos/gallon = $15.31 US.

And tonight I retrofit yet another Megawatt with caliper dial 10-turn pot, and all the upgrades. Going web surfing for a 100 ma scale 4" Simpson ammeter. Going to put that Manganin shunt to work. Wish I had a 12" x 5" X 5" box to stuff it in.

SCVJeff
Explorer
Explorer
Here's another one I heard:

Maรฑana does not mean tomorrow..
It just means Not Today
Jeff - WA6EQU
'06 Itasca Meridian 34H, CAT C7/350

MEXICOWANDERER
Explorer
Explorer
I like doing things once. I found years ago lazy engineers tend to make stuff that does not fail. A second design workup is too much needless work. It did not take me long in life to figure out a krap part with a lifetime warranty is only intelligent if the store is within walking distance of the failure, and the parts supply and store will be around forever. A three dollar socket returned using six dollars in gasoline or shipping is a stupid (excuse me, financially unwise) choice. Quicksilver, goes to Brenda and Jesรบs, which will end up being like an apartment. How they managed to hot galvanize dip a 38' bus I will never know, but if kept electrically isolated from earth ground. the coating plus 11 pounds of zincs will keep the steel from rusting. The salt air acts like a conductor for the zincs to protect.

When I rebuilt alternators 100% of them were superior in durability and lifespan to the original. Can't do that anymore - Transpo, and Renard stuff is made in China garbage now.

But this controller and the LED lights, I hope they all are operating in 2030 long after I am gone. Mexico is not the land of surplus electronics and exotic materials. Indeed the moniker for the country could read: Just - Get - By

happycamper002
Explorer
Explorer
Wow!!!
That was pretty slick. Your statement has enormous relevance to the subject, in terms of suitability of each particular item that will resist: Fungus , corrosion, push button life span, oxidized contacts, dissolving critical parts of switches and intolerable high humidity etc.

Sure, life in the tropics is tough. And you don't have to go very far. Just go to Hawaiian Islands south of Honolulu and you will experience it first hand. Outside the problem of deterioration of any man made material, locals had to contend with howling 150 mile-an-hour wind. Mosquitoes/flies that will almost lift you airborne off your comfy hammock.

But let's go back to the issue. All of the scenario you brought up should have been mentioned on your first question.
In it, you indicated that your criteria was to build something that will look like a finish product that is fit for a princess' living room: flashy flush mounted membrane switches, glow orange light, no visible oogly toggles and rockers etc.

Relevant response came forward and I thought they were fantastic. However, in the end you are telling everyone that you require specs that amount to building a battleship, replete with military specs and completely immune to harsh environment.

This goes as well for the 24 volt requirement (which you should have mentioned) in the first place.

I don't know if you've been in the service.

Twenty four volt vehicles , including buses (yes they they do have buses in the military base.) that shuttle military families inside the base to different areas like schoolhouse, gym, PX center etc., are ever present.

These 24 volt vehicles were adapted by the military to achieve compatibility among different vehicles like personnel carriers, amphibious vehicles, including humvees etc. These vehicles run on diesel.

Being high compression engines and effect of oil viscosity that they are, they require glow plugs before you crank the engine. 24 volts is very efficient for this purpose.

I had a diesel Mercedes sedan that had two batteries that supply 24 volts for glow plugs and then switches to 12 volt to match with equipment voltage for radio, ammeter and lights etc. In emergency situation you can even use a certain formulation of jet fuel that could run a diesel engine.

Not efficient but will get you out of a bind.

This is a forum that I consider a bastion of valuable information for Rver like me. It serves those newcomers as well-- albeit enormously.
The type of discussion (and people involved) that dwell on the โ€œGOTCHAโ€ premise, doesn't reflect the noble purpose of this site. This attitude flies in the face of: โ€œI'm here to tell you something that nobody else knew.โ€ camouflaged arrogance. Totally puerile and uncalled for.

I hope you are in better shape that would not require to push that โ€œ Help, I've fallen and I can't get up.โ€ SOS button.

Your inimical eloquence maybe of some help for some, but would be something that would be at the bottom of my priorities.

MEXICOWANDERER
Explorer
Explorer
Membrane switches do poorly when tapped a hundred times a day. Push button lifespan suffers greatly in corrosive environments because they are not sealed. I had to use DeOxit blue on all my cutting edges because left on a table overnight an open window three feet away from the tools deposits a nasty sprinkle of corrosion on them. We have a perpetual sea breeze and water that never cools below 25c - a very trying combination. For my radiator fan on the car, I was replacing one relay every six months. Even in the dry, winter months. Pop the cap off the relay to find a pile of blue-green powder with a dash of iron oxide. That has been lessened with the use of genuine Tyco relays.

Even electric meter bases corrode to shards in a couple of years. Same for the housing. I am going to bring 24 cans of Rust-O-Leum bed liner my next trip north.

But household switches get eaten. I actually -pack- spec grade receptacles with silicone grease to extend their lifespan. I wish I could find "T Rated" house toggle switches. They have disappeared altogether. But Cole-Hersee to Pollack the rocker switches die, silver contact or no.

It's a tough life here in the tropics - but someone's gotta do it.

And you are correct if you guessed that spending seven dollars on a switch used twice drives me ballistic. Can't keep the windows closed as fungus would sprout and grow and no doubt become sentient.

MrWizard
Moderator
Moderator
I'm not big on membrane switches
I would use push button normally open, monetary contact
Same action more durable
Yeah times are nice, you have too install st the device pump light etc
A lot of residential lighting uses 2 way or 3 way switching
No timers no relays, just 'travelers' aka pairs of switched wires
I can explain it to you.
But I Can Not understand it for you !

....

Connected using T-Mobile Home internet and Visible Phone service
1997 F53 Bounder 36s

GordonThree
Explorer
Explorer
A microcontroller would be my solution to that scenario. One button press turns the MOSFET on and starts a timer for 15 minutes. Another press kills the timer and shuts off the MOSFET. Wire as many switches in parallel as needed.

A voltage regulator would be needed to nock the 24v down to 5v.

There's modules on eBay that do this, or regular old 7400 logic and a 555 timer could do it too.
2013 KZ Sportsmen Classic 200, 20 ft TT
2020 RAM 1500, 5.7 4x4, 8 speed

MEXICOWANDERER
Explorer
Explorer
imagine this...

A waterproof water pump switch above the sink - and in the bathroom. The wonder of latching relays.

Porch light switches in the living room and in the bedroom (the wonder.........)

When I pulled wire in this bus, I parallel pulled extra lengths; living room to bedroom bathroom to bedroom. I even ran twisted shielded pairs from lights to switch. Only 18-gauge but they'll do.

The reason why I can not drive at night any more is I have managed to lose all my night vision. Over my work area, I have a 37-watt LED flood, a 26-watt CFL plus an articulated arm 6" magnifying glass with 20 watts of LEDs. I -could- remove the switch plates and drill holes and install a 470 ohm resistor then an LED but this does not allow for the "3-way switch" action of a latching relay. Plus it would look awful. I have brown rockers now that try to match the teak veneer. The new bezels are slightly larger than the old switches.

Switching this way allows the luxury of installing one shot timers. Like 15-minutes for bathroom, 15-minutes for cargo area (behind where the rearmost seat used to be when it was a school bus). No more "forgotten" lights.

And yes, I have one good hand to grab with. Like it or not I have joined the "Helllp I've fallen and can't get up!" crowd. That ad still makes me laugh. But instability especially at night, doesn't. I can hang on with the right hand a zero-in with the point left index finger.

Now I have to figure out today's birthday feast that is low fat, sugar and sodium free that won't make me gag. Twinkies with NutraSweet, and Coca Cola Zero?

In case you wonder - my son in law helps me tremendously with the installation of things like this. He is eager to learn and I am eager to teach.

happycamper002
Explorer
Explorer
MEXICOWANDERER wrote:
To clarify:

The vehicle is 24 volt. The lamps are a pair of series 12-volt each a total of twelve doubles. If I am not mistaken Arduino is a 5 volt control?


You can get a 3-32 volt Arduino solid state relay (rated 40 A) but if you go with the capacitive switch they are rated 5-12 volts.
Come to think of it, there is no pilot light.

Maybe they make it now,I'm not sure.

MrWizard
Moderator
Moderator
i'm sorry, this seems like a lot of work for nothing
do these switches need to be lighted, when the water pump etc is NOT on
changing the switch and going to all electronic control, will not alter the amount of power the pump uses

IF you really have the physical need to use membrane switches for water pump etc
how do you manage to do all the things you do now ?

is this the case of needing 'a reality check' ?

if current switches are worn out, replace with something that use an LED for lighting the switch, so you know its on
I can explain it to you.
But I Can Not understand it for you !

....

Connected using T-Mobile Home internet and Visible Phone service
1997 F53 Bounder 36s