Hobby Electronics Basics

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Mixing 4000 and 7400 Series

Hi, I have a circuit that is made up of 4000 series CMOS ICs but it needs a magnitude comparator to work and I only hav...
3 comments posted 18yrs
posted by mQiQcQhQaQeQlQ
3 comments posted 18yrs posted by mQiQcQhQaQeQlQ

45 Volt DC Power Supply

I need a 45 volt DC power supply for a tube regenerative radio, but don't like the idea of using 5 9 volt batteries. I...
11 comments posted 18yrs
posted by the1930s
11 comments posted 18yrs posted by the1930s

Printer with Step-up transformer not working

I have an HP 2100tn printer that works on 220V and I use a 500W step up & down transformer between it and my outlet. Th...
11 comments posted 18yrs
posted by Searcher7
11 comments posted 18yrs posted by Searcher7

Do receiver antennas need matching or not?

Hi All, I always hear that antennas have to be matched to their radio, but in receivers (such as FM and shortwave radio...
42 comments posted 18yrs
posted by billcalley
42 comments posted 18yrs posted by billcalley

100KB sliders

I'm repairing a (music) keyboard because the 100 KB sliders are shot. What does the "B" mean? It's a 100 k ohm pot. Doe...
13 comments posted 18yrs
posted by rabiticide
13 comments posted 18yrs posted by rabiticide

Beam interruption / time measurement

It's been many a year since I've messed with electronics -- back when a nice color television used maybe a dozen 6GH8A...
7 comments posted 18yrs
posted by not
7 comments posted 18yrs posted by not

Regenerative Radios (Again!)

I've found a suitable regen radio circuit that only runs off 12 volts. I've already decided to buy a regen radio using...
10 comments posted 18yrs
posted by the1930s
10 comments posted 18yrs posted by the1930s

Two AC questions

Consider in the first case, I have a ground potential sticked on a simple AC circuit, with a AC source and a linear res...
8 comments posted 18yrs
posted by jl
8 comments posted 18yrs posted by jl

lm317 help

So I'm looking at the datasheet for the LM317: http://www.national.com/mpf/LM/LM317.html and I realize I don't have a 2...
6 comments posted 18yrs
posted by mrdarrett
6 comments posted 18yrs posted by mrdarrett

Isolation transformer?

I have a 450VA isolation transformer. The transformer is supplied from a three prong outlet. I've taken some measuremen...
3 comments posted 18yrs
posted by spamme
3 comments posted 18yrs posted by spamme

LED Circuit?

I'm trying to apply a tally light system: a Panasonic video switcher that sends a signal, and I want a couple of LEDs t...
1 comments posted 18yrs
posted by drorworld
1 comments posted 18yrs posted by drorworld

LEDs different current/voltage

Hello, From what I've read in the many basic tutorials on LEDs, you can wire different color LEDs in series on a single...
14 comments posted 18yrs
posted by nospam
14 comments posted 18yrs posted by nospam

DC to DC converter

Suppose you have a device (HF transceiver) that requires 11.7V to 15.8V DC to run and you want to run it from lead acid...
15 comments posted 18yrs
posted by 1qazse4
15 comments posted 18yrs posted by 1qazse4

Real Over Unity Motor Design Theory

Just remember this, a transformer is designed for a purpose and it can be either a step up transformer or a step down t...
4 comments posted 18yrs
posted by elgersmad
4 comments posted 18yrs posted by elgersmad

what enclosure to use ?

Hi All I built a super-regen radio and want to enclose this in a box of some sort. I have two options - 1. Plastic box...
3 comments posted 18yrs
posted by shelton.dcruz
3 comments posted 18yrs posted by shelton.dcruz