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Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members. |
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22nd Jan 2023, 8:12 pm | #1 |
Nonode
Join Date: Jun 2016
Location: Bognor Regis, West Sussex, UK.
Posts: 2,288
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HV Boost converter module
I have bought one of these modules to see if it can be adapted to use as a valve HT supply.
It is available from several suppliers including e-bay, amazon and Aliexpress. Search for: "DC12V to for 200-450V 70W High Voltage Converter Boost Step Up Power Supply" I have traced the schematic, see attached. (the value of some of the capacitors is guesswork) I am sure that the chip is a uC3848AN device. The chip is only marked with chinese characters which Google lens translates as "Select Electronics" I am puzzled by the function of Q2, this seems to be switched hard on when the supply voltage exceeds about 3V and connects the input 0V to the output 0V. If this is functioning as an undervolt protection then it is superfluous as the 3848 has a low voltage protection built in, it will only run if the input volts is above 7V. Any thoughts welcome. Peter |
22nd Jan 2023, 8:38 pm | #2 |
Hexode
Join Date: Mar 2020
Location: Rochdale, Greater Manchester, UK.
Posts: 440
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Re: HV Boost converter module
Interesting that the fuse is also in the negative circuit, and the diode across Q2 will be conducting?
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22nd Jan 2023, 8:50 pm | #3 | |
Nonode
Join Date: Jun 2016
Location: Bognor Regis, West Sussex, UK.
Posts: 2,288
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Re: HV Boost converter module
Quote:
I have double checked that part of the circuit and it is correct. Peter |
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23rd Jan 2023, 12:25 am | #4 |
Nonode
Join Date: Oct 2010
Location: Tintinara, South Australia, Australia
Posts: 2,324
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Re: HV Boost converter module
It is for polarity protection in case somebody swaps the +/- input supply.
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23rd Jan 2023, 8:30 am | #5 |
Nonode
Join Date: Jun 2016
Location: Bognor Regis, West Sussex, UK.
Posts: 2,288
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Re: HV Boost converter module
That makes sense.
For my application I can link it out then. That would free up the MOSFET to connect in parallel with the output device. With another gate resistor to prevent parasitic oscillations of course. I am also going to try adding an overwind to get a negative supply for grid bias. See proposed circuit. Peter |
23rd Jan 2023, 9:45 am | #6 |
Dekatron
Join Date: Feb 2009
Location: Chesterfield, Derbyshire, UK.
Posts: 3,737
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Re: HV Boost converter module
Hi Peter good luck with it, the one I tried wiped out most of the AM bands, Mick.
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23rd Jan 2023, 12:25 pm | #7 |
Nonode
Join Date: Jan 2009
Location: Bristol, UK.
Posts: 2,059
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Re: HV Boost converter module
Are the resistor values in the output divider string right?
dc |
23rd Jan 2023, 12:59 pm | #8 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
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Re: HV Boost converter module
These converter modules are somewhat noisy but with a few outboard components like ferrite chokes and feedthrough capacitors and additional screens they can be made RF- quiet enough to be incorporated into receivers without any major problems. I used one of the smaller ones recently to replace the failed vibrator power supply in my 1950s era R209 comms receiver.
__________________
I'm the Operator of my Pocket Calculator. -Kraftwerk. |
23rd Jan 2023, 2:16 pm | #9 |
Octode
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,567
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Re: HV Boost converter module
Well as it says 40 watts continuous I thought I would buy one to try out on my TX unit, nothing to lose for that cost.
Thanks for the circuit as well. Adrian |
23rd Jan 2023, 5:11 pm | #10 |
Nonode
Join Date: Jun 2016
Location: Bognor Regis, West Sussex, UK.
Posts: 2,288
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Re: HV Boost converter module
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24th Jan 2023, 2:58 am | #11 |
Nonode
Join Date: Oct 2010
Location: Tintinara, South Australia, Australia
Posts: 2,324
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Re: HV Boost converter module
Re post #5 pdf - Why have you got a 5k resistor - R13 - in the source of the FET you've reallocated?
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24th Jan 2023, 4:09 pm | #12 |
Nonode
Join Date: Jan 2009
Location: Bristol, UK.
Posts: 2,059
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Re: HV Boost converter module
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24th Jan 2023, 4:13 pm | #13 |
Nonode
Join Date: Jan 2009
Location: Bristol, UK.
Posts: 2,059
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Re: HV Boost converter module
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24th Jan 2023, 5:37 pm | #14 | |
Nonode
Join Date: Jun 2016
Location: Bognor Regis, West Sussex, UK.
Posts: 2,288
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Re: HV Boost converter module
Quote:
Peter |
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