VHF Circuits
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A typical circuit at 20 MHz is shown. The crystal, which has an internal series resistance Rs of 14ohm, oscillates at its third harmonic. The diode clamp Dl and D2 provides a constant amplitude control. .. -
The range of this transmitter is about 50 feet with a short whip antenna. The tone generator, is made up of a unijunction transistor, Q1, and R1, R2, R3, and C2. Transistor Q1 pulses on and off at a rate determined by the time constant of R1 and R2,.... -
This VHF VCO circuit is suitable for 30 to 200 MHz. Q1 can be replaced by a 2N3563 for operation above 100 MHz.. -
The MAR-x preamp shown will cover up to 1.5 or 2 GHz with the correct MAR-x IC. ATTN1 should be omitted for low noise-figure.appli cations. ATTN1 and ATTN2 provide a means of limiting possible termination range,.. -
The Jammer is a very small circuit and can fit inside a small plastic box with 9V battery inside. It can be very illegal if you attach an external antenna so don't. adjust frequency by turning trimmer. It is intended only as a practical joke device. The.... -
The picture shows the JFET VHF band of super-regenerative receiver circuit, where high discharge tube V1, V2 for the super-regenerative detector tube, IC1 is a low frequency amplifier. Circuit and sensitivity than 1uV, static power consumption less than 10uA... -
A 'TV modulator' is really no more than a transmitter. It is a very small transmitter, admittedly, but none the less that is what it is. What does a modulator actually do? In general -and this design is no exception to the rule - it is a simple oscillator.... -
This simple counter is useful for frequency measurements of various wireless equipments, especially transmitters, receivers and signal generators in VHF/UHF band... -
This Field Strength Meter is simple and also quite sensitive. It uses an ordinary digital voltmeter to measure RF signal strength up to a few hundred MHz. The multimeter should be set to the lowest dc volts range for maximum sensitivity. This is normally.... -
This is a wide band signal strength meter circuit which responds to small changes in RF energy, designed to be used for the VHF spectrum and will respond to AM or FM modulation or just a plain carrier wave. This circuit measures radio field strength by.... -
This circuit is a powerful video sender in VHF band. The modulator section is designed to operate on either channels 7 to 13 or 14 to 29. For channels 7 to 13, L1 and L2 are 3 turns of #22 wire wound on a 3/16 inch form. For channels 14 to 29, L1 and L2 are.... -
The circuit presented here is a simple audio/video transmitter with a range of 3 to 5 metres. The A/V signal source for the circuit may be a VCR, a satellite receiver or a video game etc. A mixer which also operates as an oscillator at VHF (H) channel 5 TV.... -
This circuit is a RF modulator which can be used for modulating of video signals. The P1 controls the Light and the P2 controls the contrast of video signal. The RF modulated output signal can be received on the VHF band ( about 189 MHz ). Note that the.... -
The RF circuit is a C-Class power amplifier . it is used in last stage of transmitters .Its maximum power output is about 1 Watt . the circuit can be used in 3 frequency range 30-100-200MHz... -
This circuit is useful to amplify and distribute video signals with low noise and without losses. The CA3100 is a fast opamp designed to amplify video signals. Set the P1 to control the input signal level to have a clear picture on the TV set... -
Many times we needed to strengthen a small signal in the region of VHF or FM. The preamplifier that to you we propose offers 20dB in all the region of VHF and it still can reach also their 500MHZ. The amplifier is a circuit of high frequency RF with.... -
The circuit is a modified Colpitts oscillator, tuned with MV209 varactor diodes. The resonating inductor and the drain choke are selected by a rotary switch. 1N5711 Schottky diode, D, clamps the maximum positive voltage on the gate of oscillator FET, Q1 to.... -
Here is a nice little receiver for narrow-band FM reception. It can also be used to receive FSK, RTTY and PACKET signals from the HF bands. Basic receiver sensitivity is in the region of 1uV PD and the receiver can be tuned to almost any frequency from.... -
When the start switch is pushed, the output of the charger goes to 14.5 V. As the batttery approaches full charge, the charging current decreases and the output voltage is reduced form 14.5V to about 12.5V, terminating the charging process. Transistor Q1.... -
This project is a miniature, VHF FM (wideband) Wireless Microphone transmitter of the type that are commonly refered to as BUG's. Note that "BUGS" are illegal but "Wide-Band Frequency Modulation Wireless Microphones" (WBFMWMs) are not, as so many people have.... -
Once again my collection of projects creation has been interrupted by another necessity. Patrick and other people have asked me for a circuit of a VHF power amplifier. These circuits are my "standard" building blocks that can be used to amplify RF power.... -
A few designs for remote control switches, using VG40T and VG40R remote control pair, are shown here. The miniature transmitter module shown in Fig. 1, which just measures 34 mm x 29 mm x 10 mm, can be used to operate all remote control receiver-cum-switch.... -
A very simple and efficiency active antenna electronic project can be designed using this electronic schematic circuit that is based on transistors. This active antenna electronic project is useful for a wide range of RF frequencies covering three RF bands.... -
A high efficiency simple 2-transistor VHF amplifier electronic circuit project can be designed using this electronic circuit diagram. This VHF amplifier electronic circuit has a very high efficiency of about 16dB gain, and requires no tuning or alignment.... -
A very simple low cost and ultra compact VHF UHF Low-Noise amplifiers circuit can be designed using the MAX2664 and MAX2665 ultra-compact LNAs for VHF/UHF applications. These devices incorporate a broadband LNA with an integrated bypass switch. The MAX2664.... -
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This amplifier has VHF (very high frequency) and UHF (ultra high frequency) response, you can use it for receiver booster for example. Here is the schematic... -
Together with a good directional antenna this high performance two-stage antenna amplifier for the VHF FM broadcast band will enable you to capture far rem... -
This circuit uses an oscillator (2N2222) and a diode Dl as a nonlinear mixer. The frequency is set by a slug in Ll. RFCl, Cl, and RFC2 form a low-pass filter to pass video and block rffrom the video source.. -
Remote control using VHF modules. A few designs for remote control switches, using VG40T and VG40R remote control pair, are shown here. The miniature transmitter module shown in Fig. 1, which... -
We all know how a dip meter works and what it measures - the resonance of an LC circuit. The circuit featured here is designed to work in the VHF range. The tester coil is inserted in the LX terminals and placed near the LC circuit to be tested. The variable....
New Circuits
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This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of.... -
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is.... -
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to.... -
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This.... -
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the.... -
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,.... -
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the.... -
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power.... -
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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The principle behind a metal detector is really very simple. Proof of this is the circuit that...