HiIf you feel really adventurous, try just an 18 Volt transformer, and connect an LED between pins 13 and 9 (+ end to 9).,, Approximately 5 mA to LED - can change one of the 2.7 K resistors to adjust brightness. Never tried it, so I don't know how difficult to put an LED in for the strobe. Just an idea....
Hi
So only now I got my hands on it after buying new 18v transformer.
I tested the turntable for few days and it works well.
Now I feel sure enough to go ahead deal with the stroboscope LED.
Can i just connect to points 9 and 13 as you said?
What about discconect the voltage doubler?
Is it necessary?
Remind you that with the new transformer I'm not feeding any 70v...
@elnaldo , @sregor
Thanks!
By the way, I will just do as you said, but honestly I don't understand and can't imagine the circuit.
What will be the LED circuit in this case?
+25v from the point #9
What's next in the circuit? One of the resistors? Q01? How do you get the required 5mA to the LED?
I would be glad for explanation.
Thanks!
Thanks!The led is fed by +25V DC, then a couple of resistors limiting the current, and then a transistor that closes the circuit to ground at the strobe freq. Without that switching transistor, the circuit would be : +25V >> Led >> resistors >> ground, and the led would be lit all the time, no strobe effect.
You can jump one of the of the 2.7K resistors, it will double the current at the Led, within a very safe value (around 10mA) and make it brighter.
If it doesn't work, check the led polarity, and perhaps the transistor circuit needs more current to work. But you'll see that once the Led is installed.