A neon tube cannot be dimmed as easily as an incandescent lamp because the tube can start only at a voltage much higher than the mains, after which it will remain lit at the mains voltage. The level of both the starting voltage and the working voltage depends on the temperature of the tube. Normally,[…]
Read moreAuthor: bilal
Digital tape counter
The tape counter described gives a ten-step indication with the aid of two ICs and a seven-segment display. Its great advantage is that it can be connected to a recorder in a straightforward manner since it records the length of time the motor runs. The motor of the cassette player is connected to the reset[…]
Read moreMetal detector
This detector will help you find fairly large objects that consist of materials with a relatively high permeability. Also, it indicates whether the magnetic object inside the detection coil has good or bad conductive properties. Examples of materials that couple good magnetic properties to a fairly high electrical isolation are ferrites pressed from metal oxides.[…]
Read moreTelephone monitor
The modern telephone can easily be connected in parallel, enabling a household to have one in the bedroom, kitchen and hall or study. It is, however, not always easy to see (or hear) at one position whether the phone at one of the other positions is in use or has taken up the call. The[…]
Read moreFront-to-rear wiper coupling
On some cars, it is convenient to couple the rear window wiper to the windscreen wiper. However, since the rear window does not get nearly as wet as the windscreen, particularly when the car is moving, the rear wiper should operate only once for every umpteen wipe of the windscreen. Note that your car may[…]
Read moreWater pump control for solar system
In most small solar power systems using a boiler, it is required that the water circulation pump is not switched on until the temperature of the collector (the solar panel) exceeds that of the water in the vessel. Here, a two-sensor monitor is presented that enables this condition to be met. One sensor is fitted[…]
Read more4-digit counter module
This compact four-digit digital counter is suitable for any application, such as clocks, frequency meters, digital voltmeter, tachometers, stop-watches, scoreboards, etc. The counter module provides a reset switch and a carry output signal. The maximum count of the module depends on which version of the IC used: • the MM74C926 pulls its carry output high when[…]
Read moreSuper starter for cars
The super starter makes it possible to start cars with ageing batteries and obsolescent (coil-based) Ignition systems, particularly during cold or damp weather. During starting, the voltage of an ageing (and possibly cold) battery will be insufficient for the coil to generate a tension high enough to create a strong spark across the spark plugs. The circuit[…]
Read moreHorse simulator
Here is a way of faithfully reproducing the movement of a horse: with a rotary switch that enables selection of step, trot, gallop to the, gallop to the left and background. The manner in which the horse puts down its hoofs is indicated clearly by LEDs. The simulator forms, therefore, a versatile demonstration model for[…]
Read moreCar lights alert
Virtually modern cars have a built-in alert alarm to warn that you have left the lights on when you are getting out, There are, however, millions of older cars that have no such useful device and their owners might find the present circuit just what they’ve been waiting for. The anode of diode D1 is[…]
Read more