to build has been included here. Many simple transistor configurations like,
rain alarm, delay timer, set reset latch, crystal tester, light sensitive
switch and many more have been discussed in this article.
you will come across many small very important transistor configurations,
especially designed and compiled for new budding electronic enthusiasts.
simple circuits to build (schematics) shown below have very useful applications
and are yet easy to build even for new electronic enthusiasts. Let’s begin
DC power supply:
A very nice adjustable power supply unit may be built using just a couple of
transistors and a few other passive components. The circuit provides good load
regulation, its maximum current being not more than 500mA, sufficient for most
This circuit is built around just two transistors as the main active
components. The configuration is in the form of a standard Darlington pair,
which increases its current amplification capacity hugely. Rain drops or water
drops falling and bridging the base with the positive supply is enough to
trigger the alarm.
free power supply:
For many audio amplifier circuits hum pick-ups can become a big nuisance, even
proper grounding sometimes are unable to rectify this problem. However, a
high-power transistor and a few capacitors when connected as shown can
definitely curb this problem and provide the required hum free and ripple free
power to the entire circuit.
circuit also utilizes a very few components and will faithfully set and reset
the relay and the output load according to the input commands. Pressing the
upper push switch energizes the circuit and the load, whereas it is deactivated
by pressing the lower push button.
A very simple yet very effective timer circuit can be designed by incorporating
just two transistors and other handful of components. Pressing the push ON
switch instantly charges the 1000uF capacitor and switching ON the transistors
and the relay. Even after releasing the switch the circuit holds on the
position until C1 is completely discharged. The time delay is determined by the
values of R1 and C1. In the present design it’s around 1 minute.
Crystals can be quite unfamiliar components especially with the electronic
novices. The shown circuit is basically a standard Colpitts oscillator
incorporating a crystal to initiate its oscillations. If the connected crystal
is a good one, will be indicated through the illuminated bulb, a faulty crystal
will keep the lamp shut.
Level Warning Indicator: No more peeping and nervous apprehensions with
overflowing water tanks. This circuit will produce a nice little buzzing sound
well before you tank spills over. Nothing can be as simple as this one.
giants, I mean simple circuits to build with huge potentials.
Pretty confident regarding your hand dexterity? The present circuit can definitely
challenge you. Build this circuit and just try sliding a constricted metal ring
over the positive supply terminal without touching it. A buzzing sound from the
speaker will entitle you with “antsy hands”.
If you are interested to build a low-cost light dependant switch, then this
circuit is just for you. The idea is simple, a presence of light switches OFF
the relay and the connected load, absence of light does exactly the opposite.
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