Dr Ronald Stiffler SEC technology

[Slider2732]

Nick - it's actually one of my vids that your circuit came from
https://www.youtube.com/watch?v=2omcrkrrhoc
It can be confusing though, because Lidmotor came up with the 4 pin crystal circuit and the one I showed was found on a website a few days later. It's by KF50BS, which is presumably his Ham radio name.


All who noticed the funky scope display - The scope appears to be fine, all normal measuring results in normal traces. It only does that weirded out thing on this booster circuit.
The Ground from the scope lead is attached to the Ground of the boost circuit, which itself is connected to the Ground of the AD9850 or 2 pin crystal circuit. Common Grounds being important in these things...at least so i've always thought. Have got no problem with being wrong though if it clears up the output and scope trace !

Or is this a forehead slapping doozy of a thing ?
That because the input voltage for the sig gen or 2 pin crystal circuits is 5V and the input for the booster is 15V, the Grounds should be separate ?

[Slider2732]

Have now connected the scope Ground to the booster Ground and disconnected that link between the AD9850 and the booster.
It's still wonky 
Next thing will be to separate all wires as far away from each other as possible. Then shorten to be as small links as possible, then get some coax and try that for connections, then dump the boost circuit into a bath of kerosene and ignite it

Pics show the output from the AD9850+booster at 15V, at 20V and the 1kHz built-in scope test.
N.B. the scope never actually shows 13.6MHz, it will always flick between 13.5 and 13.7

[gyulasun]

Hi Itsu,

My bad, somehow I missed your post #555 and commented only your post #561 when you were measuring the output to the LED board in the 3 coil setup. So you already gave the answers to my most questions. 

You wrote:

...
I think we don't need the DC at that middle coil, just the RF AC to excite it.
...

Well, okay but I was pondering why the shorted DC component as a result of rectification may or may not cause loss in the setup? Because the AV plug diodes rectify the RF as they should and if you place a puffer cap across the diodes output, then DC voltage remains and the RF is killed as usual.  Now there is the coil across the diodes output and the DC is surely killed (at least voltage wise) and the RF voltage remains. This is why I mentioned this. 

In the Doc's video his scope showed only a little change in the RF amplitude the probes measured (I do not mean the Math channel) when he removed the 3rd (output) coil + LED board combo,  while in your setup the RF amplitude changes about 5V (from 17Vpp to 12Vpp) when you remove the 3rd coil.  I think this may come from the small differences between your coils especially due to the small difference between the middle and the 3rd  (output) coil.
So probably the 5 Vpp change could be reduced if you replace the input and the output coils with each other: this way, after the change, the two most identical coils would be at the critical places as I think.  Of course we do not know yet whether such 5 Vpp or whatever change at the input of the 3 coil setup may prove to be unwanted or not, I mention this because in the Doc's setup such amplitude change is not seen.

Gyula

[gyulasun]

Hi Erfandl,

Your finding the current draw is reduced with the 3 crystal and the brightness increases is interesting.      Would you mind using a Pi filter in the battery supply rails? I do not really think your Ampermeter is fooled with the 3 crystals operating though.

Just connect the oscillator positive supply wire to the battery via a 1 mH (1000 uH) choke coil.  And connect one-one 10 or 22 or 47 or 100 nF capacitor across the supply rails on both sides of the choke, thus you form a Pi filter.  Such filter greatly reduces any 13.56 MHZ and higher harmonic frequencies going back towards the battery and your Ampermeter which now should be connected between the battery positive and the positive input of the choke, ok?   
Let me repeat: I do not really assume your Ampermeter shows false currents and that is why you see current reduction...  For the time being I cannot give a logical explanation. 

Gyula

[gyulasun]

   Gyula:   I measured the current on my oscillator. Without the crystal it was 22mA, and with the crystal it was 52mA.   This is with the L3 on a load of 10 leds on an AV plug. This is with an 8v input.
   For some reason, now only the 7.2Mhz crystal is doing anything. No light with the other crystals on. 
Wireless near field distance is only about 1 cm away from the L3, as noticed on the led/av plug.

Nick,

Thanks for the current measurement, it shows the transistor (I assume it is still C1815) dissipates about 8 V x 52 mA=416 mW power. This is just the 400 mW limit specified for this transistor in its data sheet at 25 degree Celsius ambient temperature. (Higher ambient temps derates the 400 mW)
So I think your transistors were killed by heat dissipation when run from 12 V supply, current was surely higher than 52 mA, causing much more than 400 mW heat in the transistor, leading to destruction.

A temporary help to reduce heat in the transistor would be to use a 82 or max 100 Ohm resistor in the collector, putting it in series with the 220 uH choke coil you now have there. This way say the 52 mA current would reduce collector voltage by 82 Ohm x 0.052 A = 4.2 V  i.e. the 8 VDC supply would become only 8 - 4.2 = 3.8 VDC for the collector-emitter section, so that transistor dissipation would change to 3.8 x 52 mA = 197 mW only,  less than half of the earlier 416 mW.
Of course, this lower dissipation remains valid for the 12 V operation too but the 82 Ohm may need to be changed a little (perhaps to 76 Ohm), depending on the actual current draw. The goal is to let a 4 or max 5 VDC working collector-emitter voltage for the transistor.

The final (and not temporary) solution would be to use transistors with higher power dissipation ratings like the BD243C type or what Itsu uses. This way normal heat sink could also be used if needed while for the C1815 it is hard to clamp on a cylindrically shaped heat sink but of course it is not impossible.

Make sure that after inserting the 82 Ohm resistor in series with the 220 uH choke, the coupling capacitor should remain connected to the collector directly as before,   for the collector point should remain the oscillator output. 

Gyula