GOOD EVENING FRIENDS. ITIS JULY 13, 2022. I CAME ACROSS AN ASSEMBLED CMC 707 WHICH THE OWNER OBVIOUSLY THREW AWAY. THIS NEVER WORKED. MANY TRANSISTORS WERE NOT CORRECTLY INSTALLED AS TO THEIR PINS. VERY COMMON MISTAKE. MOST SILICON TRANSISTORS HAVE THEIR EMITTER ON THE LEFT IF YOU ARE FACING THE FLAT SIDE. MOST HAVE ITS BASE IN THE MIDDLE. C945 HAS IT ON THE RIGHT SIDE. IT IS SIMPLE TO LOCATE THE BASE. PUT YOU TESTER ON RX 1. ONE PROBE TO THE BASE, THEN CONTACT THE OHER PINS.IT WILL BE ON-ON OR OFF-OFF IF THAT'S THE CORRECT BASE. IF ON ON, REVERSE THE PROBES AND IT WILL BE OFF OFF. MANY TESTERS TODAY HAVE A TRANSISTOR CHECKER.

THE CRYSTAL RADIO RECEIVER

HI FRIENDS, IT IS JAN 23, 2022. IT HAS BEEN SOMETIME. A NEW ACQAINTANCE BROUGHT UP CRYSTAL RADIOS TO ME AND MEMORIES JUST CAME BACK. I WAS 12 IN ZAMBOANGA CITY. FOUND A BOOK ON "FOXHOLE RADIO" AND I COULDN'T SLEEP TLL I BUILD IT. MAGNETIC WIRE AND HEADPHONES WERE THE EXPENSIVE PARTS. THE FOXHOLE RADIO USED A RAZOR-LEAD PENCIL DIODE. TOILET PAPER CORE WAS NOT A PROBLEM. I SCROUNGED TO BUY A SET OF HIGH IMPEDANCE HEADPONES. I FORGOT WHERE I GOT THE WIRES. VOILA, I BUILT IT AND IT WORKED! I PICKED UP 2 STATIONS IN THE CITY. I SAW A VARIABLE CAPACITOR IN MY UNCLE'S JUNK AND USED IT. VOILA, I WAS ABLE TO TUNE! LOOKING BACK, IT WAS TODAY'S TYPICAL CRYSTAL RADIO RECEIVER. 120 TUNS ON A TOILET PAPER CORE. ANTENNA AND GROUND ON EACH ENDS OF THE COIL. A CRYSTAL DIODE NOW COMMON, THEN A HIGH IMPEDANCE HEADPHONE. TUNING CAN BE BY ADJUSTING THE LENGTH OF THE COIL OR BY A VARIABLE CAPACITOR OR BOTH. READING ABOUT CRYSTAL RADIOS ALL THESE YEARS, I CAME ACROSS WHAT IS DESCRIBED AS ONE OF THE BEST IF NOT THE BEST CRYSTAL RADIO SET, THE THE MYSTERY RADIO THAT APPEARED IN AUSTRALIA IN 1932. IT HAD A UNIQUE GROUND TO EARTH. IT WAS NOT FROM THE MAIN TUNING COIL BUT ROM THE SECONDARY COIL FEEDING THE HADPHONE!

HELLO. TME O UPDAE THIS BLOG. I WILL POST FHE PCB GACE OF HE CMC 707 AM RADIO.

In my last post, I erased the audio amp section and the AM radio is nothing by a threwe transistor circuit. Well, we can reove the yellow IFT and the tranny after it. The white IFT connects to the rad oscillator coil. It becomes a 2 transistor radio!!! It will still work.