SCUBA Torch Circuit; why no 'off' in the toggle sequence?

[Boncuk]

Hi Klem,

as I already mentioned the HCF4027 is pretty touchy and sensitive to noise.

It may be a better idea to make a PCB.

Here is a revised circuit including the debouncer circuit.

Shorting wires instead using a switch will result in multiple triggering of the circuit, although it already contains a minimum debouncing circuit.

The HCF4093 gives clean square wave clock pulses, no matter how often you "retrigger" the input. The output swings high until you release the pushbutton + the the time determined by the RC network.

The board size has increased to a length of 88mm and a width of 21mm with one wire jump, clearly marked.

Regards

Boncuk

P.S. The PCB layout is not finalized yet.

 

[Klemheist]

Boncuk,

OK, thanks for that

One last thought before I go to work...could it also be interference/noise from the lED modules. Unlike your diagrams the LED's both have integral 'pots', DC_DC converter circuits. Could this be it?

Anyway, will be away fromt he site for a few hours so again, thanks, and talk soon

Cheers

Klem

 

[Klemheist]

Back again,

OK I have removed the croc clips and used a proper junction connections to shorten the cables. I am also using the piezo to switch the circuit.

In deliberate measured presses of the piezo this set sequence happens;

Battery power applied, both LEDs come on (every time)
A on
B on
Both on
A on
B on
Both on
A on
B on
Both on....and this repeats itself with no OFF in the sequence.

If I speed up the presses it occassionaly skips a sequence above, and very occasionally ends up with an OFF...about one in every 50 presses or so.

Klem

 

[Boncuk]

Hi Klem,

try to connect power LEDs without DC/DC converter. I suspect the DC converter (inductive load?) causes a lot of noise when being energized.

The circuit was designed to drive power LEDs directly from the power supply which also supplies the control circuit.

If you have an oscilloscope you should be able to see the tremendeously high spikes the converter produces when switched on.

Also, if unable to omit the DC/DC converter take care of sufficient bypass (470 to 1,000µF) and a reverse Schottky diode (even better a bipolar transil-diode, ST-part number 1.5KE6V8CA) directly at the converter power supply.

Boncuk