T&L Publications

Switching supplies delivering 12 V at 50 A are available off the shelf. Cost will probably be over $300. Some of these may be available in surplus for a fraction of that amount, but may be hard to find. I would not recommend attempting to design such a supply on your own. Slight errors in design usu...

Two points about Superglue:<p>It is very hard to pull the joint apart, but it is much easier to shear it. It you need to get the part loose, tap it sideways rather than pulling it. This works both ways. Arrange the part so that the joint is not subjected to shear stress or it may break loose.<p>It b...

If anyone is interested, here is a little more ancient history.<p>Popular Electronics was started as a new magazine by Ziff-Davis Publications near the end of 1954. I didn't have a subscription to it until January 1957, a Christmas gift from my father. One of his friends had all the issues back to t...

This sounds like an educational kit that I saw over 40 years ago. The components were mounted on plastic carriers that were plugged into a piece of perfboard. Connections were made by jumper wires with u-shaped clips on each end. I haven't seen it since. I believe that Heathkit made a series of trai...

Varicaps are usually nonlinear and the frequency of an LC oscillator is also a nonlinear function of the capacitance. The scale factor of a varicap VCO (MHz/volt)will probably vary considerably over the tuning range. Predicting its behaviour can be done, but it is tedious.<p>Frequency multiplication...

I have seen a very few 90 degree stepping motors in military surplus. I suspect that the torque would be quite low for these units. Stepping motors also do not like inertial loads at high stepping rates.<p>The low speeds are the problem, as well as the wide ratio of speeds, possibly 20 or 30 to one....

Connecting to the serial port would only require a single RS-232 interface chip. Connecting to the parallel port would require a UART, some logic for timing, and at least 8 data buffers and a couple more for control signals.<p>Visual Basic appears to be different from QuickBasic in the way the seria...