Hmm, I actually wondered about that. Should the nail be rusty?I would agree, maybe a few more turns.
But I don't like that nail. I don't like the way it looks.
Is that a modern nail?
Just how flux worthy is that nail?
Much easier from a PC PSU is the mains common mode choke which is already wound, some are toroid and some are E - E ferrite core. They usually have the 4 pins on a more or less square footprint, just continuity test to identify the 2 windings - linking the 2 windings in series with a link wire mounted diagonally across 2 pins will give you the correct phasing - either end can be the B or C winding.You don't have to break the tube, just separate and base from the bulb. I've done it numerous times. But I doubt you'll find a toroid. You'd have a better chance with an old computer power supply.
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Actually - a ferrite core is basically powdered rust mixed with powdered whatever ceramic they use and sintered.No, just ferro.
Irony.
I've tried several different resistor values (10, 330, 1k, 10k) and none of them made the circuit work. I think the problem is likely the poor quality of my inductor.You don't have to break the tube, just separate and base from the bulb. I've done it numerous times. But I doubt you'll find a toroid. You'd have a better chance with an old computer power supply.
The explanation of my post can be found in post #50.
Try a bundle of nails - it approximates a bit nearer to a laminated core.I've tried several different resistor values (10, 330, 1k, 10k) and none of them made the circuit work. I think the problem is likely the poor quality of my inductor.
Well, do what you think is right. But I don't see any way your circuit can start, regardless of the inductor. The transistor needs to be biased at the edge of conduction for the circuit to work. I have a feeling you didn't follow my suggestion of using a variable resistor, as you listed different fixed resistance values. I'm not saying if you do that it will work, just saying I don't think it will work the way you have it configured.I've tried several different resistor values (10, 330, 1k, 10k) and none of them made the circuit work. I think the problem is likely the poor quality of my inductor.
@Brownout: I'm confused. If that's the case, why didn't @DickCappels need a variable resistor in his flooring nail inductor circuit?Well, do what you think is right. But I don't see any way your circuit can start, regardless of the inductor. The transistor needs to be biased at the edge of conduction for the circuit to work. I have a feeling you didn't follow my suggestion of using a variable resistor, as you listed different fixed resistance values. I'm not saying if you do that it will work, just saying I don't think it will work the way you have it configured.
However, in Dick Cappels JT, transistor bias is supplied directly through the coil and base resistor. As far as a I tell from your picture, you don't do that. Your coil is grounded on one end and connected to the base at the other end. thus, you have no base bias. Also, your coil is constructed much differently than Dick's, therefore you might need more bias to get it started.@Brownout: I'm confused. If that's the case, why didn't @DickCappels need a variable resistor in his flooring nail inductor circuit?
The blocking oscillator is a bit more crude than that, basically any voltage that causes significant base current to flow will bias the transistor on and cause collector current to flow. The inductor is an auto-transformer, and by transformer action causes a large increase in base current, that in turn ensures collector saturation. When the collector current causes core saturation, the inductor loses its property of inductance - at that point, the regenerative action driving the base collapses and the transistor comes out of saturation.Well, do what you think is right. But I don't see any way your circuit can start, regardless of the inductor. The transistor needs to be biased at the edge of conduction for the circuit to work. I have a feeling you didn't follow my suggestion of using a variable resistor, as you listed different fixed resistance values. I'm not saying if you do that it will work, just saying I don't think it will work the way you have it configured.
The base winding extends from the Vcc tap to the base via a current limiting resistor. With a JT the Vcc is going to be 1.5V and with a Si transistor the Vbe is going to be 0.7V - its as simple as making the resistor big enough to limit the current to what the B-E junction can handle.Even a blocking oscillator needs transistor bias. It won't work without it. No matter what is done to the circuit in question, it won't work unless the transistor is biased above cutoff, no matter how crude the oscillator is. And the oscillator doesn't care how the transistor is biased, as long is it is biased. By using the method I described, you don't have an minimum design, but you have a working design, and you don't need to guess what bias is correct. One can then further refine the design.
Not in the TS's picture. I've already suggested he change it.The base winding extends from the Vcc tap to the base via a current limiting resistor.
Hurdle???? the TS's circuit will NEVER work as it is constructed. Instead of trolling each and ever one of my posts, why not look at his picture and make suggestions, AS I ALREADY HAVE. And I've given him options that include changing his connections so that the coil can bias the transistor. And a voltage divider is one of the simplest solutions ever devised in electronics and sure as hell isn't complicated. And as I've pointed out, it can help him to establish a proper bias point. I've gotten many a oscillator working using the SIMPLE and UNCOMPLICATED method. It's sure as hell is not a hurdle. Moreover, there isn't a single way to build a JT. Some have divider bias networks, some do not.If you are going to complicate the circuit by adding a potential divider, that by its very definition involves a shunt resistor across the B/E - the TS seems to be having enough trouble already - why add another hurdle?!!!
Not in the TS's picture. I've already suggested he change it.
Hurdle???? the TS's circuit will NEVER work as it is constructed. Instead of trolling each and ever one of my posts, .
Well, when you actually make an actual correction, then maybe you'll have a point to make. But for now, you don't.Trolling you?!!! - I didn't even take any notice of who's silly remarks I was correcting, if your silly remarks were more prolific than anyone else's you got more corrections.
I made my comments just after the TS posted a picture showing a breadboard circuit that won't work. Subsequent comments I made were at the behest of the OP, who by the way, is the person if interest here. Use the LRU method, Look, Read and Understand.The TS seems to have responded to critique of the original attempt a couple of pages of posts ago - we're talking about the circuit now that is taking the shape of a blocking oscillator JT - why you're still harping on about the TS's ill informed original attempt, is anyone's guess!
by Duane Benson
by Jake Hertz
by Jake Hertz
by Duane Benson