Electronics > Beginners
Copperless perfboard + wire wrap for RF prototyping?
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tggzzz:

--- Quote from: aneevuser on October 15, 2019, 04:04:50 pm ---In the light of the postings above, I'm just going to confirm that wireless breadboard is absolutely insidious when it comes to constructing resonant circuits: I've largely ignored the advice above, and I've continued to play around with tank circuits on breadboard, which I've been driving from a sig. gen. through a fixed resistor (I've been swapping in different values to see how it affects Q). These have been behaving largely as expected.

This afternoon, I swapped the fixed resistor for a variable, and I was baffled to see that I was now getting voltage gain from the top of the tank. It took me over an hour to figure out that in fact I'd managed to construct a series LC circuit, where the series C was due to the capacitance between the legs of the variable resistor which were in adjacent rows of the board - in fact, the circuit worked unchanged if I removed the resistor completely, and merely relied on the capacitive coupling between the rows.

This is, on the one hand, painful, and on the other, very instructive.

--- End quote ---

Excellent :)

And that's from several points of view, e.g. enquiring, debugging, learning, sharing - and a good base for future experiments!
aneevuser:

--- Quote from: tggzzz on October 15, 2019, 06:06:57 pm ---Excellent :)

And that's from several points of view, e.g. enquiring, debugging, learning, sharing - and a good base for future experiments!

--- End quote ---
Right. I'm really Mr Theoretical (more at home with the Feynman Lectures than a soldering iron-kinda-guy) and even getting a tank circuit to work reliably at AM frequencies on breadboard is giving me a right schooling in practical circuit construction. And I'm finally beginning to understand why my past attempts at RF circuitry have failed - those stray Ls and Cs the books drone on about really make a difference, kiddies!
tggzzz:

--- Quote from: aneevuser on October 15, 2019, 07:20:12 pm ---
--- Quote from: tggzzz on October 15, 2019, 06:06:57 pm ---Excellent :)

And that's from several points of view, e.g. enquiring, debugging, learning, sharing - and a good base for future experiments!

--- End quote ---
Right. I'm really Mr Theoretical (more at home with the Feynman Lectures than a soldering iron-kinda-guy) and even getting a tank circuit to work reliably at AM frequencies on breadboard is giving me a right schooling in practical circuit construction. And I'm finally beginning to understand why my past attempts at RF circuitry have failed - those stray Ls and Cs the books drone on about really make a difference, kiddies!

--- End quote ---

Yes indeed!

Wait until you look at microwave circuit elements, e.g. stripline filters where the inductors don't have loops and the capacitors are just inductors with a different aspect ratio :)

The combination of theory and practice is more exciting than either on its own.
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