Electronic – Changing film capacitors to ceramic capacitors in pulsed induction metal detector

Multilayer ceramic capacitors (MLCCs) are actually quite good at high frequency operation by the nature of their inherently parallel construction (minimizing inductance and ESR). The type of dielectric used can cause significant variation of capacitance over temperature and applied voltage. Surface-mount varieties can crack under thermal and mechanical stress.

Film capacitors are also good for high frequency, have self-healing capabilities and excel at 'pulse' applications. They're also leaded devices, giving them advantages over surface-mount MLCCs in terms of size (read: higher capacitance values) and durability (they don't crack). The dielectrics used also don't tend to lead to large capacitance variations due to thermal and DC bias changes.

To me, given the choice of a film cap over a ceramic, I'd use the film. Space constraints can make ceramics the only practical choice under some conditions, but I'll use a film anywhere I can make it fit.

Relax. First off, the link does not necessarily point to a carbon assortment - the description does not say. What it does say is that the assortment replaces an earlier kit which did use carbon comps.

Regardless, for what you're doing there is no difference. The composition of the resistors has nothing to do with your problem.

And what is your problem? At a guess, you're reading the color codes wrong. I recommend you get a cheap mulitmeter (you can get them for less than $10 on eBay), and use it to check your resistor values.