This TV transmitter will handle frequencies up to about 250MHz, so it will work perfectly if you have
on your telly. In principle, the transmitter should work up to 500MHz or more, using the BF959 bipolar transistor. You should be able to generate a signal on UHF channel 21, but I have not (yet) tried this with the first rats-nest version.
TR2 and TR3 may be difficult to get, but you need to select a small-signal transistor with an ft=1.1GHz (1100MHz). For 50/200MHz bands you may be able to... Read Full Story
Now this is an interesting amplifier and can be built for almost any AF power level you want from or more. I will give you suitable examples for the 30 – 100watts version.
RV must be set to minimum resistance before application of power. To set up the amplifier, advance RV SLOWLY whilst monitoring the DC current through R7. Set RV for about 40mA. If you have a digital voltmeter then you can adjust for 8mV accross R7 and R8. If this standing current becomes too high (more than 80m... Read Full Story
The circuit is very simple, it just has three transistors, but the transistor types have been changed for VHF/UHF transistors. You can use 2N2369, BSX19 or BSX20, or any small signal transistor with an “ft” of typically 400MHz or more. The transistor DC biasing is a little more tolerant to varying transistor types than the old V5 (FM)
TR1 is a simple audio transistor, such as the BC547, BC108, or 2N2222. This transistor provides absolutely no gain, but it inverts the video ... Read Full Story
This power amp has a power output of 400 w
Power supply Voltage amps 400 w
+ / – 70v and 1.5 V input sensitivity
If you want a power amp 400 w
choose the perfect audio component of good Read Full Story
EPROM progrogramer does NOT use any device to output a voltage to the PC printer port, only a current sink. All inputs from the printer port are buffered. In this way there is little or no possibility of damage to the printer port, even with most wiring error possibilties during construction. This EPROM burner will handle most standard EPROMS, but some switching may be required by the constructor at the EPROM socket. I will leave that up to you, although I do give some advice on this subject... Read Full Story
This power amp has a power output of 150 W (8 ohms) or 200 W (4 ohms)
Voltage supply + / – 52v and 1.5 V input sensitivity
If you want 150W Power Make perfect audio amps choose good quality components
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It is a simple Colpits oscillator, but it has a 78L05 5v regulator (not shown) as the supply feed. The 22K and 33K resistors bias TR1 emitter to about 3v DC, which means that TR1 emitter can feed the CD4040 counter input directly when the synth is fed from a 10 volt supply. This is the “sense” output. TR2 is a buffer with an additional 4K7 base feed resistor to further buffer the oscillator from the output stage. The output from TR2 emitter is about +10dBm.
L1 determines the freq... Read Full Story
Given that the diode can be made to conduct, or not to conduct, simply by the choice of applied voltage polarity, then it must be possible to use any diode as a switch. So if you want to follow me, then just wire together the following circuit on a bit of breadboard, or something.
Set the signal generator to 1v RMS (3v peak-to-peak) at 1kHz. Set the oscilloscope to 1v/cm and set the timebase to 200uS/cm (0.2uS/cm). You will see an undistorted sinewave on the scope, and having an amplitude of... Read Full Story
