Sniffer xr 71 convert 24 volt!

[loukilouk]

this board is the same as mine: https://www.geotech1.com/forums/atta...7&d=1482604559

[loukilouk]

So if I change the irf740 transistor to some other eg 2sk1317, 1500V 12A 100 watt or some other igbt type then will I be better or not? With the same 12 volt battery or should I increase the power supply?

After a search I found 1):
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If i replace IRF740(N FET 400v 10A) with BU508A(NPN 1500v 8A) in transmitter section can reach more depth.

I mean with Increasing power(Voltage here) more depth can be obtained?

Kt315 said:
additionally you will need setting a transformer in Base of the NPN like you see this decision-section in TV sets. it will give a more controlling current in the Base, because NPN is controlled be current, not by voltage like MOS-FET. or you can try Darlington type BU808DF, no need to set the transformer in this case. there are much mos-fet's besides IRF740, BTW. 2SK1120 2SK727 are 1000V, for example. 2SK1317 is 1500V.

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And: 2)
Tepco said:
If someone really want to play with high voltage pulses in this, or any other detector, there are two simple ways, I tried them successfully. First is to replace MOSFET with high voltage IGBT transistor, drive requirement is about the same, 1200v device will clamp at some 1.35-1.4KV. Additional benefit is reduced capacitance, depending on transistor used (no need to be 50Amp rated, some modern smaller device in TO220 package). Disadvantage is increased loss, due to 2-3V saturation voltage. Another method is using MOSFET (can be low voltage type) and high voltage bipolar transistor, like used in CRT horizontal scan stages, in ?€œcascode?€? connection. Works perfectly, flyback can reach 1.5-1.8kV or even more, capacitance is slightly lower. Disadvantage is somewhat higher current consumption, large base current is needed, due to very low current gain of HV bipolar, usually less than 10. In both cases, some precaution is needed, damping and protection resistor, diodes etc, also very short high energy pulses will tend to deteriorate metal film resistors after some time. I don?€™t think all this is particularly useful in detector like delta, attempt to speed it up this way, but in some other designs may be interesting to experiment. Most obvious ?€œimprovement?€? in delta can be redesign to some other type input amplifier, to get rid of lF357 (too noisy!), not tried.

[loukilouk]

Ok thank you again!

[eclipse]

https://www.geotech1.com/forums/showthread.php?8003-Delta-Pulse

Do a thread search on "voltage" this may come up with the information you need.

[loukilouk]

I had looked there too! But I couldn't find a plan for the conversion. If you can put a link or plan? Thank you!

[eclipse]

Well actually It's been discussed in the Delta Pulse thread. You can find the answers there.

[loukilouk]

Did I make it difficult for you?

[loukilouk]

It is supposed to only power the 24 volt output mosfet, the rest with 12 volt power circuit. So what's wrong? Thank you!

[eclipse]

Trying to operate the device more than 18V will cause damage, so please don't do that.

[loukilouk]

Hello! I am a new member and do not have much knowledge of electronics. Can anyone tell me if this design is right to convert the sniffer to 24 volts?
https://postimg.cc/HJqKYvFs
If anyone has any other schematic to convert to 24 volts, let him put it here if he wants.
My pcb is: https://www.geotech1.com/forums/atta...3&d=1504014696
Thank you!