Connect Toroid to project

ThomsCircuit

Well-Known Member
LED Flasher Project:
I put this together and of course it does not function as it should. The LED is supposed to flash after you momentary short the header pins. I would like your help in connecting the toroid to the breadboard correctly so I can rule out it being the possible reason for it not working.

I also do not have a 1nf (C2). The next value I have is [10nf]. I also have a [0.1nf] How crucial is this? Could I use the 10nf?

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This is my interpretation of the authors schematic.



This is the authors schematic.


The toroid I wound. The matching 2 dots represent the wires have continuity. The numbers I gave them have no relation to the schematic.


This is my Breadboard. The red dots represent where the toroid goes.
 
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You could use 10 nF and change R2 to 220 kOhm and it should work the same as the time constant between C2 and R2 will be the same. It will use a tiny amount more current.

As far as I can see, the numbers in the photo of the toroid correspond to the numbers in the circuit diagram. 1 connects to 2, and 1 and three both go through the middle of the toroid in the same direction.

The circuit is a "Joule Thief" (https://en.wikipedia.org/wiki/Joule_thief) with an added oscillator to make it flash. I can't see what is controlling the voltage on C3 so I would be worried that might get too large.

I would try getting the Joule Thief bit working first without the IC or C3
 
Diver300 said:
As far as I can see, the numbers in the photo of the toroid correspond to the numbers in the circuit diagram. 1 connects to 2, and 1 and three both go through the middle of the toroid in the same direction.
Click to expand...
So I connect the toroid like this. I numbered the dots. And my toroid photo just happen to match up. Cool


Diver300 said:
I would try getting the Joule Thief bit working first without the IC or C3
Click to expand...
so there is a way to test the toroid. Would it be making one of the more simple designs as i see in the link you posted?
 
ThomsCircuit said:
so there is a way to test the toroid. Would it be making one of the more simple designs as i see in the link you posted?
Click to expand...
You can do a basic turns ratio test, but will need a way to generate a sine wave (AC) as a test signal.

Apply a voltage into the highest winding, the lowest winding should produce a voltage matching the ratio. For example, if you have 10 turns on one winding, 5 turns on the other, the turns ratio is 2:1.
So if you put 10v AC into the winding with 10 turns, the other winding should produce 5v AC.

BTW, you probably should have wrapped the toroid core in mylar tape before winding, to prevent scratches from possibly shorting the winding(s) against the core.
 
eTech said:
BTW, you probably should have wrapped the toroid core in mylar tape before winding, to prevent scratches from possibly shorting the winding(s) against the core.
Click to expand...
I thought of applying some clear nail polish but these have a pretty thick green coating. Thank you for the advice.
 
ThomsCircuit said:
I thought of applying some clear nail polish but these have a pretty thick green coating. Thank you for the advice.
Click to expand...
The toroids are either non-electrically conductive ferrite or iron powder imbedded in about 2% epoxy. The iron powder is soaked in a phosphoric acid solution and then dried to electrically insulate each particle. That said, the chance of any leakage of a toroid is very low. Measure the resistance of another toroid if you have one.
 
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ThomsCircuit said:
like an open circuit.
Click to expand...
Yes, if see automatic winders and the 12-gauge sold copper wire scrape strongly against the core with no impact on the performance. The "enamel" (typically polyurethane or polyester coating) gets burnished a bit but no ruptures of the coating and the cores CAN'T have (SHOULDN'T HAVE!) bulk electrically conductivity or you would get significant heating from Eddie current losses. High quality inductors are made with high quality materials.
 
Beau Schwabe said:
You can also try and swap the polarity of one of the coils. It's possible you have one of the phases backwards .. especially if you are hand winding the coils.
Click to expand...
Yes. That was another issue. I had read "swapping" but it was unclear what, then I read an article here about a joule thief and a member asked the author where the polarity marks were. I took a closer look at my work and saw the two asterisk symbols. A good lesson learned.
 
The Joule Thief circuit is one where the transformer polarity (or is it phase?) is important. There are many application where transformer polarity isn't important, so people can use transformers and not know about the phase markings.
 
Diver300 said:
The Joule Thief circuit is one where the transformer polarity (or is it phase?) is important. There are many application where transformer polarity isn't important, so people can use transformers and not know about the phase markings.
Click to expand...

Most transformer applications aren't polarity sensitive, but oscillators (as in this example) obviously are - you need positive feedback for an oscillator, and getting the polarity wrong gives negative feedback.
 
Diver300 said:
There are many application where transformer polarity isn't important, so people can use transformers and not know about the phase markings.
Click to expand...
Some times I think I'm wasting time with these projects that catch my eye. But I always end up learning something. I will be fabricating about 6 and placing them in my security cameras, (active and faux) to help deter bad actors.

PCB 25 X 60mm

 
Modified PCB to include an access hole for toroid wires to pass through and solder them from the back side. I mirrored the markings to match the top silkscreen. I thought it would make it easier to swap if polarity was incorrect.
 
It's a good thing those old CD4xxx had 2 stages of Clamp diodes with large series resistors to prevent the SCR latchup effect in CMOS when you drive Vdd thru a cap which is already biased at Vdd/2 on the input. The Absolute max when exceeded caused the CMOS to latchup.


 
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