The following diagram is the schematic diagram of 4 transistors FM transmitter circuit designed by Paul K. Sherby. Components List: R1,R2,R8 = 1K R3 = 100K R4 = 150K R5,R7 = 10K R6 = 220 ohm R9 = 10 ohm P1 = 5K trimpot D1 = 1N4002 Q1,Q2 = 2N3904 Q3,Q4 = 7001, NTE123AP C1… Read More »
In the above circuit diagram, a CMOS operational amplifier (op-amp) controls the current via a P-Channel HEXFET power transistor (IRF9520) to maintain a constant voltage across R1. The current is given by: 1 = VREF/R1. The benefits of this configuration are:
This is a mini FM transmitter built and powered using 2 transistors, designed by Tony van Roon. This small transmitter is simple to build and its transmissions could be picked up on any common FM radio. It possesses a range of approximately 1/4-mile (400 meters) or even more, depending on the line-of-sight, obstructions by big… Read More »
Above circuit diagram is a easy, simple and cheap switching voltage regulator which has capability to deliver adjustable voltage output range of 1.8V to 32V and static electric current of 3A. This regulator use adjustable regulator IC of LM317HV and a power PNP transistor of 2N3792.
This is the positive voltage regulator circuit with PNP Boost transistor: The IC8211 presents the voltage reference and regulator amplifier, while Q1 will be the series pass transistor. R1 defines the output current of the IC8211, while C1 and C2 present loop stability and as well act to suppress feedthrough of input transients to the… Read More »
Here the simple, low cost and easy audio booster circuit. It uses a transistor of 2N3392 ad the main amplifier. Component List: R1 = 47K R2 = 470K R3 = 10K R4 = 560R R5 = 270R C1 = 0.1uF/25v C2 = 3.3uF/25v C3 = 470uF/25V P1 = 100K Q1 = 2N3392 D1 = 5mm.… Read More »
The following diagram is the circuit diagram of voice transmitter which use FM signal carrier to transmit the vioce signal to the FM receiver device. Components List: R1 = 4.7K R2 = 330 ohm C1 = 0.001uF (1nF) C2 = 10-40pF C3 = 4.7pF Q1 = 2N3904 L1 = see text Misc = Electret mike,… Read More »
This is the circuit diagram of low forward-drop rectifier. A TMOS power FET (Q1) and a LM393 comparator provide a high-efficiency rectifter circuit. When VA exceeds VB, U1’s output becomes high and Q1 conducts. Conversely, when VB exceeds VA, the comparator output becomes low and Q1 doesn’t conduct.
I’ve found some interesting schematic of load cell amplifier. As we know, load cell amplifier is pretty expensive with fair price range of 100-300 USD. You may built your own load cell amplifier to get the lower cost. Here the two scheme diagram of load cell amplifier circuit: Load Cell Amplifier using AMP04: source: http://cgi.ebay.com/Load-Cell-Amplifier-Improved-Better-Stability-New-/350451149452