Posted on Saturday, October 25, 2014 • Category:
Stepper Motors
H-bridge is frequently used to control DC motors and stepper motors. When controlling a bipolar stepper motor, two full H-bridges are needed. There are many H-bridge ICs (like L298, MPC17529 and SN754410 which is a quad half H-bridge) for just that purpose. But if you are on a budget, you may want to consider building a dual H-bridge yourself. The following schematic shows a simple dual H-bridge using eight general purpose transistors (2N3904 and 2N3906). Given the maximum current of roughly 200mA, this circuit can be used to drive a small bipolar stepper motor operating between 5V and 12V, such as the stepper motors found in most floppy drives and CD / DVD drives.
Posted on Tuesday, August 26, 2014 • Category:
FM Transmitters
Presented FM transmitter is built around low power PLL transmitter and amplifier that boosts its signal all the way up to 6 Watts. The signal is amplified by three RF stages of amplification. In the first and second stages of the transmitter one of the best driver transistors were used 2SC2053. You can use the other transistors but only up to 500mW of power. In the third stage 2SC1971 RF transistor was used to achieve 6W of power. For making any RF transmitter circuit at least two meters are necessary, one is frequency counter and the other is RF field strength meter for which the schematic is provided.
Posted on Friday, August 22, 2014 • Category:
Amplifiers
This is battery powered amplifier based on LM386 chip and has an input buffer that is feeding the inverting input. The input buffer helps to retain treble details going into the LM386 chip. It is powered from a single 9V battery.
Posted on Sunday, August 17, 2014 • Category:
Miscellaneous
This is a low voltage 12V fluorescent inverter for powering two 20W or single 40W fluorescent tube. It's a circuit you can put together from junk box components and is a very simple to build. The transformer is hand-wound on a ferrite rod from an old transistor radio and the winding wire can be salvaged from an old transformer. The cost of powering the circuit is about 22 watts and this will produce the same light output as 60 watt incandescent light bulb.
Posted on Sunday, August 3, 2014 • Category:
FM Transmitters
The figure shows a schematic of an easy to build FM transmitter circuit. Mostly all FM transmitter circuits you will find online or in books require some kind of hand build inductor/coil and after building the transmitter you have to adjust that coil and trimmer capacitor a little to adjust the transmitter to transmit on your desired frequency.
If you are looking for an easy or simple FM transmitter circuit in which you don't have to make a coil with your hand then the circuit given here is ideal for you. The circuit is using a ready made 1uH inductor which can be purchased from an electronic components store. These inductors are mostly look like resistors. The circuit also does not require a trimmer capacitor, because we have used a fixed value of 39pF capacitor in the place of trimmer capacitor. We have already calculated and used the values of coil and capacitors of oscillator to broadcast on FM band, so you don't have to do any further adjustments and tuning after building the circuit. The circuit can be operated with 9 to 12 volt DC. For antenna use a 12 inch wire or for maximum range use a 30 inch wire and make it vertical.
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