How can I replace a touch switch with one lead with a toggle switch?

[David4321]

I have a light mounted underneath my desk to illuminate equipment there. It has a touch-sensitive switch which is always turning on when I brush it with my knee, which is very annoying. I opened it up, hoping to disconnect the switch, and connect a simple toggle switch to the leads, and mount that on the side of the housing. But I discovered that the touch switch has only one lead going to it. Can I actually still do the operation I planned, and if so, how to wire it? Below see photos. Many thanks for input.

 

[rjenkinsgb]

A switch like that senses either electrical "noise" pickup, or when the touchpad is capacitively grounded.
There is no simple, guaranteed way of changing how it works.

You could just move the bit of copper foil to eg. the blank area at the bottom of the case in the photo, so it's harder to touch by accident?

Or bypass the switch board and fit a switch between the red battery wire and the red wires to the lamp sections?

Before doing that, first try connecting them very briefly, and verify that the lamps are no brighter than normal. It does not look like the switch board does any power regulation, but just on the offchance it does, do not bypass it if the lamps are significantly brighter with the wires linked, as it could then damage them.

 

[Kerim]

Perhaps inserting a small switch in series with the lead of the touch switch helps.

 

[David4321]

Thanks for the replies folks,

I think I will just put a switch on one of the battery leads. It seems the touch switch will have to stay, because the device defaults to off when battery is removed and replaced, but at least I'll have an anti-nuisance switch. Putting a strip of white electrical tape over the touch switch reduced the sensitivity significantly.

 

[Tony Stewart]

It would be easier and quicker for me to drape some material or alum. foil over the sensitive area, leaving only a less exposed area for touching. That could make it more sensitive depending on how the foil is coupled near ground.

What you plan to do seems more to defeat the purpose of a sensitive touch switch.

(Edit) I see tape worked. Add enough to perfect it or fold back the copper foil

Design-wise , I am guessing it senses is a rise in 50/60Hz signal from E-fields radiated by your finger using your entire body as an antenna. Alternative methods include generating a low RF (HF) signal and reflecting back that signal with some finger capacitance.

 

[David4321]

Urgh, I finally got around to doing this, and it's not working out. I got a latching push-button switch, mounted it in the housing, cut the red lead from the battery compartment in the middle, and connected the red and black leads from the switch to the two ends. (Black to batteries, red to board.) Now what I've got is this: on first press of button, light switches on, but in lowest brightness. (The light has three brightness levels, switched by subsequent presses of the touch-sensitive button.) But after that, pressing the new switch does nothing, no on, no off, no level changes. When on, I can use the touch-sensitive button to turn on or off, but no level changes. If I pull batteries, then replace, first press turns on again, but same result. I don't actually need the two lower settings, I'd be happiest if I just had the new button do on and off of highest brightness - but could accept new switch as power interrupt, and touch-sensitive switch as controller, as discussed. Could I just bypass the board and touch-sensitive switch altogether, and get simple on/off at full brightness by just leaving button black to batteries, button red to both bulbs, and black from bulbs to white from batteries?

One thing - the new push-button has four leads, as it's illuminated; one red, one black, and two blue. I assumed that the blue leads were to feed the led, and the black & red for circuit, so thought if I just taped off the blues, and used the black & red, it would work (I don't care about the led illumination). But as it is wired, the illuminated ring is on, so maybe I am mistaken? (I tried to find a simple two lead switch, but couldn't find one of the size and type I want, with pre-soldered leads - I wanted to avoid soldering leads to button myself.)

 

[AndersonEllis]

I have a light mounted underneath my desk to illuminate equipment there. It has a touch-sensitive switch which is always turning on when I brush it with my knee, which is very annoying. I opened it up, hoping to disconnect the switch, and connect a simple toggle switch to the leads, and mount that on the side of the housing. But I discovered that the touch switch has only one lead going to it. Can I actually still do the operation I planned, and if so, how to wire it? Below see catfish photos. Many thanks for input.

Connect the hot wire to the "common" terminal on the toggle switch. Then, connect the load wire to one of the "load" terminals on the switch. If your toggle switch has multiple load terminals, it doesn't matter which one you use.
If your toggle switch has a grounding screw, you will need to connect the bare copper wire from the electrical box to this screw. This will ground the switch and prevent electrical shock.