Baracuda broken

[waltr]

Sounds like the problem.
Do double check the pin out of the +5V regulator you are using. Not all regulators of similar part number have the same pin-out. Different manufactures can and do have different pin-outs.
Also, ensure you are looking at the pin-out diagram correctly, some show from top of reg others show from bottom.
Guess how I know this!!!

[BKY1337]

Yes maximum is 200khz and 50Vpp.

I think i found the faulty part. I can measure 7.8Volts at the Output of the +5V Voltage regulator with 9Volt battery.
I have 11.2V there with my 12V battery.

I think the circuit works ok because 7.8 is still in the range where the other part of the circuit works but 11.2 is too much.
I dont think that 11.2V can destroy anything.

I need to wait until i have a new one.

[kt315]

A good 10x probe would be better than a resistor divider due to capacitance but only if the circuit to be measured can be loaded, and thus change characteristics like when measuring the Self Resonant frequency of a coil.
--
self resonant freq is 500-600kHz while a range of his pocket oscope is 200k.

[waltr]

A good 10x probe would be better than a resistor divider due to capacitance but only if the circuit to be measured can be loaded, and thus change characteristics like when measuring the Self Resonant frequency of a coil.

A 10X probe divides the Voltage by 10 so you must READ the scope's manual, or what is printed near the inputs, for what the MAXIMUM Voltage allowed. Then multiple the MAX Voltage by 10 and ensure this is greater than the maximum Voltage in the circuit to be tested.

But as homefire stated: in a PI detector the only place where the Voltage will be high is directly on the coil right after it is switched off. It then 'flies-back' to a few hundred Voltage.
This is where I use a resistor divider as I described to ensure the Voltage the scope sees if safe.

[BKY1337]

Can i use such a 10x Probe with my DSO? https://www.ebay.de/itm/Tastkopf-Pru...8AAOSwnNBXXSm1

Is it better than two resistors?

[homefire]

Your DSO 150 will work fine anyplace but the coil it's self with a 10 X Probe. Without the 10X you can still look at the output of the first Amp.

[waltr]

I have only a DSO150 , i fear that i can damge it with too high voltages.

Then use a couple of resistor to create a Voltage divider to ensure the DSO is safe. Use high enough resistor values to ensure current limiting.
I use a 79k and a 1k to divide Coil fly-back to lower level.

Something is wrong

Sure sounds that way.

[Andi68]

Something is wrong

[BKY1337]

I measured the transistors instead of the voltage converters.

I got -7.8V for the 79L05 and 18.8Volts from the Output of the 78L05 with my 12V Battery.

[BKY1337]

I can measure 0.41 kHz at Pin 4 40106.

TP1 is 10V. I think i could connect it to my DSO.

Drain of 78L05 = 0Volts
Drain of 79L05 = -2.45Volts input is -11.7V from the LT1054 <---- Damaged?

[BKY1337]

LT1054:

Pin8: V+ Battery 12V
Pin5: Vout -11,7V

I dont know what Pin7 is but i had 2,66kHz there.

Is this Output ok???

LF412:

Pin4: -4.98V
Pin8: 11,9V

Mosfet:

Gate: 0.71kHz
Damping Resistor is 330R
Mosfet is cold without Coil.

I have only a DSO150 , i fear that i can damge it with too high voltages.

[Qiaozhi]

I dont know how i should measure this because i dont want to destroy something. The Mosfet becomes hot very quick.
Can i measure it without coil?

I need to look where are the Pins first.

I could measure everything with 9 Volts , but i think everything works fine with 9 Volts. It did with about 10 Volts too, but not with 12.

I dont know if it worked before the Mod because i think that my battery had only 10 Volts when i built the board.

The biasing of the MOSFET is such that it does not get stuck on if the oscillator fails. What's more likely is that the TX oscillator is affected in some way by the increased battery voltage. Perhaps you could test it using a bench power supply, and gradually increase the voltage to see what happens.

[waltr]

Yes, you can test without a coil connected. MOSFET should NOT even get warm, only current would be through the damping R.

Use your O'scope to check that ALL pulses are working properly with the correct timing.
The MOSFET gate should be switching to correct Voltage levels, 0V to +VB. Ensure the Base of the MOSFET Gate transistor is being switched.
The P-ch MOSFET's gate should be high (+VB) to be OFF and low (0V) for the TX pulse period.
+5 and -5 Voltages correct?
Oscillator running (U4)?

[BKY1337]

I dont know how i should measure this because i dont want to destroy something. The Mosfet becomes hot very quick.
Can i measure it without coil?

I need to look where are the Pins first.

I could measure everything with 9 Volts , but i think everything works fine with 9 Volts. It did with about 10 Volts too, but not with 12.

I dont know if it worked before the Mod because i think that my battery had only 10 Volts when i built the board.

[waltr]

Now i have a Problem with my Barracuda.
My battery became empty today 8x1,5V. So i know that it was almost empty when i had the 30-32cm yesterday.
So i decided to put new batteries in and the barracuda doesnt make a sound when i have the full 8x1,5V Batteries connected.
I saw that my IRF became extremely hot and the coil is humming. It wasnt before.

Its not damaged because i can connect a 9V Block Battery to it and it runs with about 20cm depht.

My parts are all safe up to 16V (15V LT1054), I changed the big capacitor to a 2200uF 16V. I have no clue whats the problem.

The batttery pack has 12,4V.

Is the LT1054 output Voltage and all other Voltages correct?

Are the Timers working?
If the Coil MOSFET is not being properly turned On/OFF then it will get hot.
Is the MOSFET Gate switching properly?