Dr Ronald Stiffler SEC technology

[gyulasun]

Nick, 

I clearly described in my above post what voltages up to the C1815 could be OK and now I copy and paste the relevant text to here again:

"The 'rule of thumb' for such oscillators that have a coil in the collector is to use transistors rated for collector emitter voltages (V_CEo) with at least 3 times higher ratings than the supply voltage applied. The V_CEo for the 2SC1815 is specified as maximum 50 V, so 50/3= 16 V: so the supply voltge should be below 16V to be on the safe side."   

And now you simply deduced: "They are OK for voltages of up to 8v or so." 

I am simply clueless whether you understand what I write, sorry to say this. Or just negligence? Can you explain how the 8V came? 

Gyula

OK, well now I can see why the 20v 5w solar panel would blow these C1815 transistors. They are OK for voltages of up to 8v or so. When using the 100k base resistors, but only provide about 12v or 13v output at the collector emitter, which is not enough on my oscillator to see some wireless effects.

  I have set up some additional series connected 10k ohm resistors to see which number of them will provide the needed current to the base. That is after going through the 100k base resistor and crystal.
  So if the question is how much current should go to the transistor base, while using let's say 12v input. I don't know the answer, yet.

[NickZ]

  Perhaps what makes me say so is the pile of dead C1815 that I have in front of me. Most died at 12v, using a base 100k resistor, or they become untouchable in one minute running time.
  I am running a input of 12v, the C1815 transistors are rated at 50v. And I'm using the recommended 100k resistor on the base.
It's suppose to work at those voltages. And, at times it does.
But, I've been looking for transistors that can handle more input, and to see which crystal provides for the highest output. So far it's about 14v output from the 7.2MHz, on my oscillator when running on 4v input, and about 30v output, at 12v input.
  Otherwise, all is fine at 4v input, the crystals all run perfectly at their rated frequency, and the transistor is cool, and does not blow.

  Yes, it's negligence. But, I'm looking for what works for me, and the parts that I have available at the moment. Not that easy to do.
   I hope that gives you a clue, as to if I understand you, or not. In any case, not to worry,  I'll get it going right, yet.   
   Maybe a Snickers Bar would do you well, also.  While I try to do better...

[gyulasun]

Nick,

All I can suggest kindly is: acquire as much knowledge as you can by self education.

If you are looking for what works for you, then that is also okay but it is a hard way.
I really wish you good luck and very little number of bristles on your way.

I like Snickers Bars too.   

Gyula

[NickZ]

   It seams like the oscillator works to provide the output voltages, but I don't see any wireless at 8 volts input, and 12v cooks the transistor. I'll try a trim pot on the base next to see if I can run at higher voltages without blowing the transistors.
   I also made another L3 coil, with less turn of a little thicker wire, about 60 turns, so that I can remove some if needed.
It seams to work better than my previous L3, but still no wireless at 8v input. 8v is where the C1815 works, a bit hot, but not overheating. The 13.5MHz crystal provides for less output at 8v input (21v), than the 7.2MHz (at 27v), 12v input provides 38v output at the collector emitter. Yet, no wireless, or practically none.  Anybody else having the same situation???

[erfandl]

Hmmm. increased the brightness by paralleling three 13.56 MHz crystal