Please help the Mechanic

[johnnie52]

Hello,

Being new to this forum and to electronic design in general, I hate to start out by asking for help, but I'm desperate at this point.

I am a qualified mechanical designer who has been thrust into the job of designing simple PCB electronic circuits due to a recent down turn in business and myself being the only person available who has even the smallest amount of knowledge about circuits.

I've designed a circuit for a customer that is to be a small flash light. It has two LED's and a SPDT (ON,OFF,ON) slide switch to switch between off, and the bright and dim settings. It runs on 6 VDC (2 - 2032 coin batteries), through resistors to the LED's. The LED's are wired in series so that both of them are on in either position.

One position routes power through a single resistor, the other switch position routes power through two resistors to create the bright and dim functions.

However, my client wants to have a push button switch in place of the slide switch. I planned to attach the schematic but the forum won't let me attach an image as a new member.

I've spent a couple of days searching the web for a PC mount, right angle push button SPDT switch that will have the same action as the slide switch, (ON,OFF,ON) OR On Dim, On Bright, Off. So far, I have drawn a blank. It can be either momentary or latched as long as it stays on without being held until it cycles back to the off position. Also, the switch may NOT have the usual panel mounting hardware like a threaded nose with a nut or panel mount tabs.

I have very little real estate on the 1" x 1.5" board. Can anyone suggest a switch that will replace the slide switch and provide the action that is needed to transfer the current between the resistors?


Signed,

Frustrated Mechanic

 

[johnnie52]

I almost forgot

The switch needs to be a through hole type rather than SMT.

 

[audioguru]

It won't be easy.
Use a CD4017 sequencer IC to count to 3. It is driven from a push-button de-bounce circuit. The sequencer drives two transistors.

A microcontroller can be programmed to do what you want and drive two transistors.

 

[Boncuk]

Hi Johnnie52,

I tried to place the parts around a CD4017 including a pushbutton of 6X6mm size and a debouncer circuit for the switch.

I used the SMD version of the counter and also 2 SMD transistors. There is still room left on a 1X1.5" board. Using pure SMD design (capacitors and resistors as well) the entire board size can be halved.

If you want me to design a board for you just PM me the desired shape and the position for the LEDs, the batteries and the pushbutton.

The design can be single sided with a few jumps. All parts will be placed on the solder sider except for the wired parts.

Boncuk

 

[Boncuk]

Hi again,

it just came on my mind. There are pull switches used in lamps with series contacts. The switching is normally:

first pull: one lamp on
second pull: second lamp on
third pull: both lamps on
fourth pull: both lamps off

If you convert it to to a push switch you're done.

It's also easy to wire. for the both lamps on just parallel another resistor.

Boncuk

 

[johnnie52]

Thank you both for your help. Like I said, I'm only just starting to learn about electronic circuits and have no formal electronics training. I'm trainied in the mechanical disciplines of machinery design. You know, the nuts and bolts of machines, not the brains.

I have to use through hole LEDs due to the customer's desire for the lights to be inserted into the plastic body of the light. It just seemed like it would be easier from a manufacturing stand point to make the entire board in through hole rather than a combination of SMT and TH. When I've reached the point where the forum will allow me to attach images I'll show you some pics of what I'm trying to accomplish.

I'm about ready to inform my client that if he insists on a push button switch, it will cost him way over his $5.00 per board limit.

 

[neophyl]

You could use these
**broken link removed**
They are a off/on/on click switch that duplicates a simple slide switch. Ive used in the past to do an off/low/high light using luxeon type leds.

Very cheap and the shipping is fairly quick from China considering its free. Works out about 20-25p each so worth a go.