JimJ
5,000+ posts
Tangled Up in Blue
Whomever can build me a little circuit for a project I'm doing...//content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif I'm just too busy lately with other things, plus I don't have a 'scope to properly tune it up.
notes from the designer...
XTAL - crystal
Q1 - 2N3053
Q2 - IRF510 or IRF511
R1 - 100K ohms
R2 - 68 ohms. .5 or 1 watt rating.
R3 - 2200 ohms, but anything from 1K to 10K is OK here.
R4, R6 - 10 ohms
R5 - 1000 ohms. adjusts gain of modulator. lower this value as needed.
R7 - 1K to 470K, depending on the Z of the input source.
C1, C2 - 82 picoFarad, but anything from 82 to 120 pF is OK. Silver mica type is best.
C3 - .01 mfd. disc
C4 - output shunt capacitor. for 3.9 mHz; 680 to 1000 picoFarads, 100 V., for 7.2 mHz; 470 picoFarads, 100 V. Values will be on the lower side, unit will be operating in the 6-8MHz range
C5 - 1200 picoFarad, silver mica, 100 V., But a compression trimmer capacitor
that covers up to around 2000 pF is best, for tuning up.
C6 - 47 mfd., but anything from 10 to 470 mfd. is OK here, and just a low voltage
rating is needed, 3 V or greater.
C7 - .1 mfd. disc ceramic
C8 - RF bypass capacitor, .1 mfd. disc ceramic or film. Put a few of these along the Vcc line.
C9 - RF bypass capacitor on modulated Vcc, .1 mfd. disc ceramic or film, but anything from
.1 to 1 mfd. is OK, with a 30 V rating or more.
C10 - audio bypass capacitor, 470 to 1000 mfd. electrolytic, or greater, with a 15 Volt or more rating.
C11 - .1 mfd.
C12 - 1000 mfd. or greater electrolytic, with a 12 volt or greater rating.
C13 - 1 mfd., but anything from 1 to 10 mfd. is OK.
D1, D2 - 15 volt zener diode. This is an optional protection circuit, to clamp
out any induced voltage from T1, when the Vcc is interupted.
L1 - flyback inductor, 24 turns of AWG #20 on a T50-2 core. Radio Shack p/n 273-102 works
well here, or any similar inductor.
L2 - for 3.9 mHz, 16 turns. for 7.2 mHz, 11 turns. AWG #20 on a T50-2 core.
L3 - for 3.9 mHz, 40 turns. for 7.2 mHz, 23 turns. AWG #30 on a T50-2 core.
T1 - see drawing below. re-wound this auto-transformer using magnet wire AWG #21, the first section
with 60 turns, then I lost count on the next section after I dropped it, and it came un-wound a bit.($#@%!)
So I just finished and scramble wound another 70 turns or so, for the "hot" side going to the transmitter.
It's not picky. just get it close. It would probably work OK with less turns.
Say 40 turns the first section, then 45 for the section going to the transmitter,
using AWG #22 or so magnet wire,
on any transformer core that can be taken apart easily.
If you're interested, PM me and I'll give you the details of it, like parts layout, where to find the harder-to-find parts (like crystal holders and RF connectors)...
Thanks.
notes from the designer...
XTAL - crystal
Q1 - 2N3053
Q2 - IRF510 or IRF511
R1 - 100K ohms
R2 - 68 ohms. .5 or 1 watt rating.
R3 - 2200 ohms, but anything from 1K to 10K is OK here.
R4, R6 - 10 ohms
R5 - 1000 ohms. adjusts gain of modulator. lower this value as needed.
R7 - 1K to 470K, depending on the Z of the input source.
C1, C2 - 82 picoFarad, but anything from 82 to 120 pF is OK. Silver mica type is best.
C3 - .01 mfd. disc
C4 - output shunt capacitor. for 3.9 mHz; 680 to 1000 picoFarads, 100 V., for 7.2 mHz; 470 picoFarads, 100 V. Values will be on the lower side, unit will be operating in the 6-8MHz range
C5 - 1200 picoFarad, silver mica, 100 V., But a compression trimmer capacitor
that covers up to around 2000 pF is best, for tuning up.
C6 - 47 mfd., but anything from 10 to 470 mfd. is OK here, and just a low voltage
rating is needed, 3 V or greater.
C7 - .1 mfd. disc ceramic
C8 - RF bypass capacitor, .1 mfd. disc ceramic or film. Put a few of these along the Vcc line.
C9 - RF bypass capacitor on modulated Vcc, .1 mfd. disc ceramic or film, but anything from
.1 to 1 mfd. is OK, with a 30 V rating or more.
C10 - audio bypass capacitor, 470 to 1000 mfd. electrolytic, or greater, with a 15 Volt or more rating.
C11 - .1 mfd.
C12 - 1000 mfd. or greater electrolytic, with a 12 volt or greater rating.
C13 - 1 mfd., but anything from 1 to 10 mfd. is OK.
D1, D2 - 15 volt zener diode. This is an optional protection circuit, to clamp
out any induced voltage from T1, when the Vcc is interupted.
L1 - flyback inductor, 24 turns of AWG #20 on a T50-2 core. Radio Shack p/n 273-102 works
well here, or any similar inductor.
L2 - for 3.9 mHz, 16 turns. for 7.2 mHz, 11 turns. AWG #20 on a T50-2 core.
L3 - for 3.9 mHz, 40 turns. for 7.2 mHz, 23 turns. AWG #30 on a T50-2 core.
T1 - see drawing below. re-wound this auto-transformer using magnet wire AWG #21, the first section
with 60 turns, then I lost count on the next section after I dropped it, and it came un-wound a bit.($#@%!)
So I just finished and scramble wound another 70 turns or so, for the "hot" side going to the transmitter.
It's not picky. just get it close. It would probably work OK with less turns.
Say 40 turns the first section, then 45 for the section going to the transmitter,
using AWG #22 or so magnet wire,
on any transformer core that can be taken apart easily.
If you're interested, PM me and I'll give you the details of it, like parts layout, where to find the harder-to-find parts (like crystal holders and RF connectors)...
Thanks.
