This circuit was kindly suggested to me by another blogger for a SCUBA torch I am building.
It will have two 12watt LED heads with one momentary piezo switch. I need a simple circuit that can toggle through using one momentary switch, so that the torch can have one LED on, both on and an OFF position.
This circuit with a 4027 dual flip flop and a couple of FETs acting as relays is supposed to give this sequence;
A on
B on
Both A & B on
Both OFF
In the test bed it toggles through the first three only, with no OFF in the sequence.
Can anyone please help?
(The circuit is attached and a photo of the test bed).
Can you have a SMP supply in a hand-held torch? Is it really needed for this circuit to work?
I attach modular protection circuits to the Li-ion packs... for overvoltage, overcurrent and undervoltage protection, but unlikely they perform the same function as a SMP.
Can confirm both LED's come on when battery is first connected, every time.
Also, actually got an OFF one time when toggling through multiple times. Then another time the OFF happened for a split second, then it went onto the next in the sequence
It seems to be something to do with timing, switching timing maybe.
Photo of the settup right now. Note the two bared yellow wires I'm using to mimick a momentary switch
Can confirm both LED's come on when battery is first connected, every time.
Also, actually got an OFF one time when toggling through multiple times. Then another time the OFF happened for a split second, then it went onto the next in the sequence
It seems to be something to do with timing, switching timing maybe.
Photo of the settup right now. Note the two bared yellow wires I'm using to mimick a momentary switch
- wires to power LEDs of sufficient cross section (to prevent surge on the IC-power pin)
- is there an electrolytic cap connected directly between battery and circuit?
- is a 100nF bypass capacitor connected to the HCF4027 power supply pins?
- is the piezo switch bounce free?
If all of the above questions can be answered with "YES" then try this add-on circuit. It debounces the worst quality switch and provides a clean clock pulse of minimum 50ms width.
Clock pulse time = switch operating time + RC-time
Unsure whether the cables are rated for the power draw. I've used larger speaker cables for the FET's and LED's but normal thin hook-up wire for the circuit.
No electrolytic cap between power cables. I do not need the LEDs to be OFF when first connecting the power so I didn't source it, but if this component helps with noise then I will attach it.
The 100nF across the power pins is there, although the ground cable goes from battery to the FETs first before the circuit board (if this is important)
Unsure whether a piezo is bounce-free. Looking for this through the internet it appears it might be but I see nowhere where it is clear, including the manufacturer's website. The sequence iwthout OFF is the same without the switch (just touching switch wires together), so perhaps it is unrelated to the switch.