Last
update 10/8/07
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COMPONENT IDENTIFICATION The pictures below show basic components used in the kits for people who are unfamiliar with what the different parts look like. Resistors:
The picture on the far left shows 3 different fixed resistors, a wire wound power resistor, a 1/2W 1% metal film, and a 1/4W metal film. The next picture is a pc mount potentiometer (or "pot"). A pot has 3 terminals, the two ends are the fixed value, the center contact is the wiper that varies from one end to the other. As the resistance between say the left side to the center gets bigger, the resistance between the center and the right side gets smaller, the sum remains constant. The next photo is a chassis mount pot, which in the kits is used as the audio control. Pots can have a variety of "tapers", which is how the resistance changes with respect to angle. A linear taper pot will have an equal change in resistance with change in angle. An audio taper pot has a constant change in dB when used as an audio attenuator with respect to angle (it will have a more even change in volume when turned compared to a linear taper pot which will have poor control in low volume settings). The last picture is a step attenuator, which acts like a pot but has precise settings, and is not continuously variable. The optional ones for the kits have 23 steps, 2.00dB/step. All pots have parasitic reactance (inductance and capacitance) making them less ideal than a purely resistive attenuators (22 1% metal film resistors). Capacitors
The 3 pictures on the left are various polypropylene caps commonly used to couple audio signals. They allow the audio signal (AC) to pass from one circuit to the next, but block the DC voltage. These generally have no polarity, so they can be soldered into the board either way. The auricap is a very high grade poly cap I used in the Silverbox micpres, and all custom mics we build. The difference between these and the other two shown is in most cases is unperceivable, and they are very expensive (20-30$ ea), but in extremely critical situations, I do favor them. These are supposed to be installed so that the red terminal is the input, but technically speaking they are not polarized. For the kits I don't think its worth upgrading to them since the caps we chose are very high quality also. Caps often have the value and voltage printed on them, but sometimes the capacitance value is coded. The same code is used for resistors that don't have color codes. EXAMPLE: caps is marked 225 250v. The 225 means 22 with 5 zeros behind it, or 2200000 in pF, or 10e-12. So changing from pF to uF means dividing by 1E6, or 2.2uF. Other examples: 104 = 0.1uF 333=.033uf 470=47pF The 4th picture shows various electrolytic caps. These must be installed with the proper polarity or they will blow up (far right picture). The white stripe facing the camera is the negative end (see the "-" signs in the stripe). Regulators / Mosfets
The two devices above are the LM317 3 terminal adjustable regulator, and the IRF820 moset. These are in a TO-220 package. Though they look similar, do not mix them up. Diodes
The picture on the left shows typical rectifier diodes on the (left), and zener diodes on the (right). Both are shown with the negative side up. The picture on the right is a bridge rectifier, which is composed of 4 diodes in a configuration that rectifies an AC waveform (a signal that goes both positive and negative) into one that goes only positive. When a cap is connected to the output of the rectifier, a crude DC voltage is generated (mostly DC but with AC noise) which is then generally "cleaned up" by running it through a voltage regulator (i.e. LM317). Usually these have a notch, or angled top corner, that indicates the "+" side. Like diodes and electrolytic caps, they must be installed with the proper polarity. |
