Advice needed...Polulu Toggle Circuit

Guys,

I saw this ready-made toggle circuit recommended on one of our threads.

After buying a couple and hooking them up to a 12Watt Terralux TLE-300 (3 Cree XR-E's) and using a piezo for the momentary switch...it goes on, but will not turn off with subsequent presses of the piezo.

It works fine with just bare wires for the switch; touching them together for on/off.

Can anyone help with this problem?

I tried emailing the Polulu people for help but ended up talking to a 'gifted' individual who suggested it was a "coincidence" and then likened it to a "hamburger." Perhaps he was on medication.

Guys,

This is the switch circuit I'm talking about
http://www.pololu.com/catalog/product/750

Klem said:

Guys,

I saw this ready-made toggle circuit recommended on one of our threads.

After buying a couple and hooking them up to a 12Watt Terralux TLE-300 (3 Cree XR-E's) and using a piezo for the momentary switch...it goes on, but will not turn off with subsequent presses of the piezo.

It works fine with just bare wires for the switch; touching them together for on/off.

Can anyone help with this problem?

I tried emailing the Polulu people for help but ended up talking to a 'gifted' individual who suggested it was a "coincidence" and then likened it to a "hamburger." Perhaps he was on medication.

Click to expand...

Not sure where the hamburger entered the conversation, and if he was really gifted, he would have answered your question...

The link clearly states that you may have trouble turning off at high input voltages. It sounds like it's due to either bounce at the beginning of the switch contact or limited duration of the contact. Piezo switches also have a higher resistance than other types of switches. In another thread luca brassi mentioned that APEM have piezo switches, and I saw that they have one with extended output. Maybe this would simulate the bare wires better?

You may want to try applying pressure to the piezo switch gradually. Piezos react to change in pressure. So the longer you can be increasing pressure,the better. But you don't want to go too slowly.:shrug:

D

Hi

I have recived 3 polulu toggle switch as you refer to, and used only one so far.
I have been dumb enought (could read 'buzy') to order the standard voltage version instead of Low Voltage

It currently work on a copy of Packhorse D mag, sst90 direct driven from Li-Poly 11ah (5cell 2.2ah) airplane moded battery. The switch is located in the mag cut tube. I use a reed switch activated at will by Hard disk drive Neo Magnet with a lace trought a hole.

Full charge battery are 4.20v Everything is working fine. I feed the light with 3x18ga wire, two wires are conducting +, this reduce losses when battery are full (4.20v, i get 4.05v to Circuit switch, and 3.90v to led leads (18ga). I feel the light warm in pool water.

When i first tried the circuit, i used a worn cell, witch output droped below 4.0v and circuit would not turn off even using straight push-button. With good cells, i dont have problems to turn it off.

I'll keep it anyway, as i couldn't dive so long to bring batteries dangerously low in one single dive, and i know that when i'll turn off lamp, and it would not turn off, cell will be low.

I never used piezo switches, check out with a VOM that the switch is outputing shorts when you toutch it, and not short voltage spikes (could use analog vom to get faster reads or a scope) From what i know from piezo, they output voltage spike, witch drive small mosfet embeded, thus making short on leads, for a brief time. You could have recived a piezo switch that only output spikes ?


keep us tuned, since piezo switch could be nice if you get it working. personnaly i prefer using reed from an alarm door kit, since i dont make an additional hole in my light.

I have two of the standard Polulu switch circuits. Tried it with both a LED and a 35W HID...

With the Terralux LED it turns off and on OK, when just touching the bare wires momentarily together. With a piezo however it goes on but, not off.

With a HID it turns on, but not off, even when touching the bare wires. The piezo turns on but not off.

The LED draws 12W, using a 2-cell 7.2V Li-ion
The HID draws 35W, using a 3-cell 11.1V Li-ion

Yes, the piezo shorts when pressed, and no it doesn't seem to change anything when I press slowly or hard. On the voltmeter I can see what yopu mean...slow press for fast short, hard press for longer short. Makes no difference with this circuit.

Given the diff between the LED and HID I don;t think the piezo is the root of the problem.

Does anyone use the low voltage "OFF" option on the circuit? Could that be connected somehow to help?

Does anyone use the Polulu and it works?

I'm not sure why it isn't going off. Reading the site it would appear that there is an off input where you could make a mandatory off switch if you wanted. That certainly doesn't make life easier for you but it could be setup with a simple reed switch to make it kill the light.

Re: Advice ...Polulu Toggle Circuit

mine is working allright, i'm direct drivin' SSR90, exept that i'm running on the verry low voltage side of the specs ..... will order some Low Voltage some day.

Does the forced OFF pin work in your case ?

just try the damn thing with a regular 12v bulb, it will remove any chances of any case of interferences ..... if it work as suppose, then check the following steps

maybe yours drivers are producing some ripple that turn the device crazy.
Have you tried with a diode, a choke coil, or some capacitor on the output side, since an hid driver and a led produce some noize or ripple.

keep us tuned of any clue, as im planning using these again.

TEST RESULTS
OK, I connected the Polulu switch circuit to a simple 12V 35W incandescent.

Using a 7.2V Li-ion the same happens...it goes on every time, but will only go off with bare wire touching. Piezo goes on, but no off.

Using a 11.1V Li-ion it will not switch off regardless.

I bought two Polulu standard circuits and tried them both. Both with the same results.

With the incandescent not working it would seem as if the problem is in the chip design, not noise or bounce.

The Polulu OFF contact feature does work however. But to use this we then need two switches!... One for the on, and the second for OFF.

Does anyone have any thoughts here before I ditch them with extreme prejudice!

OK, if no one has any more input let me finish the thread by summing them up as junk.

It's a sexy looking tiny PCB with SM components but inadequately designed for the high amps typical of our torches.

If you want a toggle circuit then unfortunately you will have to build your own.

dam i had high hopes for that setup, thanks.

I'll try soon my other two standard voltage both with 12v bulb and sst90 direct drive from 1cell lipoly, and give you feedback from mines

I've tried to use mine, the low voltage polulu switch.
On a SST90 direct driven by 4xAA, at about 6Amp.

It turns on, but doesn't turn of.
Not with the switch, nor with bare wires contacting.

Thinking of using a relay, as space is no issue for me.

since time, ive used my 3 different standard voltage device polulu toggle, and they are running fine with reed switch.

used two with 1s li-ion ssr90 direct driven and one with 2s with a DX 5x X-RE R2. when cells are low i get loss in the mosfet because it is out of spec. not ideal.

Ordered 15A microswitches.
You say Reedcontact (magnetic switch in tube ) would work probably?

Edit: it worked for you since using the reedscontacts? (given the voltage be within spec.)