Accurate 50Hz Oscillator Circuit Using 555 And 7490
Accurate 50Hz Oscillator Circuit Using 555 And 7490 This circuit is a getting a 50Hz pulse. It comprises a 555 timer and two 7490 divide-by-ten counter chips 7490. PARTS LISTR12.2kΩR2142kΩ (120kΩ +...
View ArticleSensitive RF Voltmeter Probe
Sensitive RF Voltmeter Probe Circuit This Circuit measures RF voltages beyond 200MHz and up to about 5V. PARTS LISTR14.7MΩR21MΩR31MΩR4100kΩR5330ΩR610kΩR710kΩVR12kΩVR22kΩC10.001µF (Disc...
View ArticleShortwave (SW) Transmitter with IC BEL1895
Here the SW transmitter circuit based on IC BEL1895. This particular transmitter circuit works in shortwave HF band (6 MHz to 15 MHz), and can be applied for shortrange communication and for...
View ArticleVlf converter
This converter uses a low-pass filter instead of the usual tuned circuit so the only tuning required is with the receiver. The dual-gate MOSFET and FET used in the mixer and oscillator aren`t critical....
View ArticleAtv Jr Transmitter 440Mhz Circuit
This low-power video transmitter is useful for R/C applications, surveillance, or amateur radio applications. Seven transistors are used in a crystal oscillator-multiplier RF power amplifier chain, and...
View Article140W amateur radio linear amplifier 2-30Mhz
This inexpensive, easy to construct amplifier uses two MRF454 devices
View ArticleTransistorized Am Radio Circuit
Shown is a schematic of a typical transistor AM radio. This circuit uses npn transistors. The circuit is generic; therefore, no specific values are given for some components.
View ArticleSwitchable Vhf Active Antenna Circuit
The AA-7 active antenna contains only two active elements: Ql (an MFE201 N-chanriel dual-gate FET) and Q2 (a 2SC2570 ripri VHF silicon transistor), which provide the basis of two independent
View Article1-Transistor FM Transmitter
R1 27k R2 56k R3 12k R4 100 C1 1u C2, C3 470p C4 6 to 10p C5 1-30p trimmer L1 etched on PCB or a center-tapped coil 5mm in diameter, 6-8 turns of enamel-coated wire 1mm thick Mic Electret microphone Q1...
View ArticleA small FM transmitter (SMD)
This SMD FM transmitter has an operating frequency of about 80 to 115MHz. Under reasonable circumstances you will be able to receive its signal at a distance of about 200 meters. Although it is...
View ArticleMiniature FM Transmitter
Additional Notes The default for the capacitors type is ceramic, preferably the npo 1% (low noise) type or equivalent. But basically nothing critical here. Use any capacitor you have laying around, but...
View Articlesimple FM Voice Transmitter
Additional Notes The default for the capacitors type is ceramic, preferably the npo 1% type or equivalent. But basically nothing critical here. Use any capacitor you have laying arround, but NO...
View Article3-3.5 Watt FM Transmitter
This is the schematic for an FM transmitter with 3 to 3.5 W output power that can be used between 90 and 110 MHz. Although the stability isnt so bad, a PLL can be used on this circuit. This is a...
View Articleamplitude modulation (AM) Transmitter
It is illegal to operate a radio transmitter without a license in most countries. This ircuit is deliberately limited in power output but will provide amplitude modulation (AM) of voice over the medium...
View ArticleFM Stereo Transmitter
This is a very easy project to build. It will transmit good quality sound in the FM band ( 88 - 108 mhz ). One inportant item is that the IC chip operates on 3 volts DC. The chip will get destroyed if...
View ArticleBand 2 VHF FM Transmitter
This small transmitter uses a hartley type oscillator. Normally the capacitor in the tank circuit would connect at the base of the transistor, but at VHF the base emitter capacitance of the transistor...
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