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Audio Auto Fade

This circuit is design, in order to is heard the voice above the music. Useful for DJ, for small radio stations, for statements above the music, in shops etc. Also we can him use in applications that we want to handle some unit with our voice. As it has the circuit has become forecast for stereo music and monophonic microphone, but can be modified and be adapted in the needs or in the use that we want, him we use.... [read more]

Precision Audio Millivoltmeter

Measures 10mV to 50Volt RMS in eight ranges Simply connect to your Avo-meter set @ 50uA range... [read more]

LED Torch

A common problem with small torches is the short life-span both of the batteries and the bulb. The average incandescent torch, for instance, consumes around 2 Watts. The LED Torch in Fig. 1 consumes just 24 mW, giving it more than 80 times longer service from 4 AA alkaline batteries (that is, up to one month's continuous service).... [read more]

Portable Headphone Amplifier

Can be directly connected to CD players, tuners and tape recorders. Tested with several headphone models of different impedance: 32, 100, 245, 300, 600 & 2000 Ohms. Schematic shows left channel only.... [read more]

Car and Motorcycle Battery Tester

Going camping nowadays involves taking lots of electronic equipment whether for day to day running or for fun and entertainment. Most of the time a charged lead acid battery and a power inverter would be used to ensure a smoothly organized holiday where ideally the missus and the children cheerfully use their electric and electronic gear! With rechargeable lead-acid batteries it’s invariably useful - if not essential - to determine whether the power source you’re hauling along on your travels is losing capacity and needs to be topped up. The same circuit would also come in handy when going on a car or motorbike trip as it can check the status of a 12 V (car) or a 6 V (motorcycle) battery.... [read more]

Small Radio Transmitter

Contains information about building a small radio transmitter, which has a PCB 1.75" x 2.5" (45mm x 68 mm) and has a range of about 30 yards or so. The documentation with the circuit says the freq range is 100-108 MHz, but I have found it to be more like 85-100 MHz.... [read more]