Author Topic: Self Oscillating Half Bridge Wonder  (Read 2339 times)

Offline kyledellaquila

  • High Voltage Enthusiast
  • *
  • Posts: 33
  • Karma: +0/-0
    • View Profile
Self Oscillating Half Bridge Wonder
« on: December 07, 2020, 04:34:49 AM »
Hey guys, I came across a rather interesting "SELF OSCILLATING HALF BRIDGE CIRCUIT" Instructables page:
https://www.instructables.com/Very-Simple-Mini-Induction-Heater-Directly-Powered/



Quote
The circuit is able to operate at frequencies of several MHZ (tested up to 12 MHz and simulated up to 30 MHz with IRFP460A) and provide several hundreds of watts of RF power (not measured directly - only by simulation and by indirect signs like heating something or lighting a bulb).
The RF power can be extracted in several different ways:
If You need high voltage - it can be extracted through a capacitive coupling from one or both sides of the main tank coil.
If You need a moderate voltage but high current, the power can be extracted in the common for all half-bridge circuits way (as shown at the picture - note the load resistor Rload). Note also that the requirements for the capacitive side capacitors (C7, C8) are high - they must endure voltages above 1 kV and reactive powers above 1 kVA.
As far as I know the circuit is novel. I've never seen before a self oscillating RF-resonant half bridge based on two transistors of the same polarity (n-MOS). If I'm wrong feel free to notify me and I will gladly include the reference.

I find this layout to be wonderfully simple and compact for the high-frequencies (few MHz) & high-voltage(few kV) it can produce...

BUT... how does it work?
How do the MOSFETs not kill their Gate-Source potential when conducting?
What guarantees that they are not switched on at the same time?
Laphicet indicates that this novel circuit solves "shoot-through currents" & "high-side switch control" problems.

Is anyone able to help shed some light on this magical wonder?

-Kyle Dell'Aquila


Offline SteveN87

  • High Voltage Enthusiast
  • *
  • Posts: 43
  • Karma: +2/-0
  • FPGA, Software Defined Radio, HV (mainly flyback)
    • View Profile
Re: Self Oscillating Half Bridge Wonder
« Reply #1 on: December 07, 2020, 12:23:48 PM »
The power stage is current-fed (due to L2) so simultaneous conduction for a short time is OK.

Nice find - I think I'll have a go on the simulator with this.

Offline kyledellaquila

  • High Voltage Enthusiast
  • *
  • Posts: 33
  • Karma: +0/-0
    • View Profile
Re: Self Oscillating Half Bridge Wonder
« Reply #2 on: December 08, 2020, 06:03:43 AM »
Let me know what you see with the simulations!
I am curious to see if you are able to make this oscillate

edit: I was doodling around with the Falstad circuit simulator and ended up making oscillations http://www.falstad.com/circuit/#%24+1+2.4999999999999998E-6+3.046768661252054+47+50.0+50%0Af+448+128+528+128+0+1.5%0Aw+528+144+528+192+0%0Aw+528+192+448+192+0%0Ac+448+192+448+128+0+4.0E-9+-2.9518273431284285%0Ar+384+128+384+192+0+10000.0%0Ac+320+128+256+128+0+9.999999999999999E-6+-57.212058505704704%0Ar+256+128+256+256+0+0.1%0Ar+384+256+528+256+0+0.1%0Aw+528+192+528+256+0%0Aw+528+256+528+304+0%0Aw+528+464+528+528+0%0Ac+320+400+256+400+0+1.0E-6+-109.43714892175667%0Ar+384+400+384+464+0+10000.0%0Ac+448+464+448+400+0+4.0E-9+-3.09826048785186%0Aw+528+464+448+464+0%0Aw+528+416+528+464+0%0Af+448+400+528+400+0+1.5%0Aw+528+304+528+384+0%0Aw+448+304+448+400+0%0Al+192+128+192+272+0+0.1+0.02979717099664517%0Aw+192+128+256+128+0%0Aw+192+400+256+400+0%0Ac+96+400+96+64+0+1.0E-5+-128.32525738816742%0Aw+96+64+464+64+0%0Aw+528+64+528+112+0%0Al+528+64+624+64+0+1.0+-0.010896322955178546%0Aw+96+400+192+400+0%0Ac+672+64+672+224+0+1.0E-6+173.78085236513266%0Ar+672+224+672+256+0+0.1%0Ar+672+256+672+288+0+0.1%0Ac+672+288+672+448+0+1.0E-6+204.78302710525008%0Aw+672+448+672+464+0%0Aw+624+464+528+464+0%0AR+752+64+816+64+0+0+40.0+150.0+0.0+0.0+0.5%0AR+752+464+816+464+0+0+40.0+-150.0+0.0+0.0+0.5%0Az+416+192+416+128+1+0.805904783+3.0%0Aw+384+128+416+128+0%0Aw+416+128+448+128+0%0Aw+384+192+416+192+0%0Aw+416+192+448+192+0%0Az+416+464+416+400+1+0.805904783+3.0%0Aw+384+464+416+464+0%0Aw+416+464+448+464+0%0Aw+384+400+416+400+0%0Aw+416+400+448+400+0%0Ac+528+256+592+256+0+1.0E-6+31.003174737826097%0Aw+624+64+672+64+0%0Aw+624+464+672+464+0%0Aw+320+256+384+256+0%0Aw+464+64+528+64+0%0Aw+320+128+384+128+0%0Aw+320+400+384+400+0%0Ac+256+256+320+256+0+1.0E-5+60.17038399264054%0Al+192+272+192+400+0+0.1+0.02979717099664517%0Ar+448+304+528+304+0+300000.0%0Ap+144+128+144+384+0%0Aw+144+384+192+400+0%0Aw+144+128+192+128+0%0Aw+592+256+672+256+0%0Al+672+464+752+464+0+1.0+0.010413042316874413%0Al+672+64+752+64+0+1.0+-0.010413042316817918%0Ao+19+64+0+35+160.0+0.4+0+-1%0Ao+45+64+0+35+320.0+0.4+1+-1%0Ao+55+64+0+34+320.0+9.765625E-5+2+-1%0A
« Last Edit: December 08, 2020, 07:11:11 AM by kyledellaquila »

Offline davekni

  • High Voltage Senior
  • *****
  • Posts: 978
  • Karma: +42/-0
  • Physicist, engineer (electronic), and hobbiest
    • View Profile
Re: Self Oscillating Half Bridge Wonder
« Reply #3 on: December 08, 2020, 06:38:08 AM »
Played a bit with simulations this evening.  It reliably oscillates with a wide range of parameters.  Performance depends heavily on MOSFET choice and modeling details.  Appears to work better with low FET gate capacitance, especially reverse-transfer capacitance (Cgd), but I haven't explored that enough to know for sure.

It does have me thinking about possibilities of self-oscillating bridge circuits.  There are situations where such would be convenient if efficiency is reasonable.  Perhaps not quite as simple, such as a self-oscillating circuit using a GDT to prevent cross-conduction.
David Knierim

Offline SteveN87

  • High Voltage Enthusiast
  • *
  • Posts: 43
  • Karma: +2/-0
  • FPGA, Software Defined Radio, HV (mainly flyback)
    • View Profile
Re: Self Oscillating Half Bridge Wonder
« Reply #4 on: December 08, 2020, 04:04:27 PM »
I used a different simulator (Simetrix Elements) and got reliable oscillation too. Yes - food for thought on self-oscillating bridge circuits.

Offline kyledellaquila

  • High Voltage Enthusiast
  • *
  • Posts: 33
  • Karma: +0/-0
    • View Profile
Re: Self Oscillating Half Bridge Wonder
« Reply #5 on: December 09, 2020, 05:28:10 AM »
I am happy to hear that you guys are able to simulate this with success!

I had some more time to fudge around with the Falstad simulator and was able to get it to oscillate. Previously I was getting errors and had to mash things around to get it to visualize. Now things are more representative of the values listed in the original diagram: https://tinyurl.com/y2o435pp Not sure if I have the MOSFETs switching properly, but it does socialite.

@ davekni, when you say that it runs with a wide range of parameters, what were you changing up? The capacitors and/or the inductor?

Do you think one could take power off of the end of the coils and rectify it for HV DC purposes? I originally came across this in pursuit for a simple method for producing HVDC on the order of 3 to 5 kv.

How would one crank up the power on this? Parallel MOSFETs?

-Kyle Dell'Aquila
« Last Edit: December 09, 2020, 05:37:12 AM by kyledellaquila »

Offline davekni

  • High Voltage Senior
  • *****
  • Posts: 978
  • Karma: +42/-0
  • Physicist, engineer (electronic), and hobbiest
    • View Profile
Re: Self Oscillating Half Bridge Wonder
« Reply #6 on: December 09, 2020, 08:19:03 PM »
I tried three different FETs, 220pF instead of 68pF, and a range of load resistors and inductor parasitic resistances.
David Knierim

Offline kyledellaquila

  • High Voltage Enthusiast
  • *
  • Posts: 33
  • Karma: +0/-0
    • View Profile
Re: Self Oscillating Half Bridge Wonder
« Reply #7 on: December 11, 2020, 04:31:09 AM »
The nature of this half bridge design seems to allow for (1)much higher HV supplies and (2)higher frequencies than say your standard ZVS circuit.
Can someone explain to me why this is the case?

Also on a side note, I found this on AliExpress today: shorturl.at/kvxAX

If I had to guess, a similar circuit may be at play here as well... Thoughts?

-Kyle Dell'Aquila
« Last Edit: December 11, 2020, 04:38:37 AM by kyledellaquila »

Offline SteveN87

  • High Voltage Enthusiast
  • *
  • Posts: 43
  • Karma: +2/-0
  • FPGA, Software Defined Radio, HV (mainly flyback)
    • View Profile
Re: Self Oscillating Half Bridge Wonder
« Reply #8 on: December 11, 2020, 01:47:20 PM »
The AliExpress link doesn't work for me, but it looks like a Tesla Magnifier. With such a small 'extra' coil, the resonant frequency will be high (a few MHz) so the half-bridge circuit you found is a good candidate for driving it in CW mode.

Offline kyledellaquila

  • High Voltage Enthusiast
  • *
  • Posts: 33
  • Karma: +0/-0
    • View Profile
Re: Self Oscillating Half Bridge Wonder
« Reply #9 on: December 13, 2020, 07:18:59 AM »
Kind of a curious thing when I was playing with my simulation:https://tinyurl.com/y38vzmjj
Once the circuit really "gets going", I noticed the high side MOSFET experiences a momentary kickback in current during its conduction cycle. I attribute that to the supply rail swinging about wildly. So I stuck a diode in line with the mosfet to see what it did. See image below:

Interestingly enough, the addition of the diode in the path caused a much stronger oscillation in the work coil. So much stronger that the voltage swings on the higher side MOSFET were exceeding 1kV.. so I started to sprinkle extra inductances in the critical paths to better represent reality which started to bring things to reality. (I also need to throw in parasitic capacitances for further realism).

My concern is that the upper MOSFET experiences a much higher drain to source voltage when compared to the lower MOSFET (due to the 100uH inductor). I imagine this is the weakness! So I tried moving around the "big" inductor to be after or before the upper MOSFET to experiment with the upper MOSFET being voltage clamped vs not clamped... or some variation in between! It would seem to me that best results are obtained when the Upper mosfet is after the inductor as shown in the original schematic. I suppose TVS diodes may be needed here to protect itself?

-Kyle Dell'Aquila

Offline kyledellaquila

  • High Voltage Enthusiast
  • *
  • Posts: 33
  • Karma: +0/-0
    • View Profile
« Last Edit: December 15, 2020, 02:31:39 AM by kyledellaquila »

Offline davekni

  • High Voltage Senior
  • *****
  • Posts: 978
  • Karma: +42/-0
  • Physicist, engineer (electronic), and hobbiest
    • View Profile
Re: Self Oscillating Half Bridge Wonder
« Reply #11 on: December 15, 2020, 03:47:56 AM »
What's the chance that the AliExpress module runs at the 13.56MHz ISM band?  That would make it a potentially useful product for plasma cleaning etc.
David Knierim

Offline kyledellaquila

  • High Voltage Enthusiast
  • *
  • Posts: 33
  • Karma: +0/-0
    • View Profile
Re: Self Oscillating Half Bridge Wonder
« Reply #12 on: December 21, 2020, 08:05:21 AM »
Quote
What's the chance that the AliExpress module runs at the 13.56MHz ISM band?  That would make it a potentially useful product for plasma cleaning etc.
A fairly good chance in my opinion.. pretty small coils going on here. I will find out in about a week or so.. I made a Christmas present for myself.
What would you clean to demonstrate useful plasma cleaning? Fingerprints or sharpie on glass?
-Kyle Dell'Aquila

Offline Acid Byte

  • High Voltage Enthusiast
  • *
  • Posts: 34
  • Karma: +1/-0
    • View Profile
Re: Self Oscillating Half Bridge Wonder
« Reply #13 on: January 04, 2021, 09:45:37 PM »
I've build many coils like the chinese one,
actually the circuit of the chinese hfsstc probably came from them watching me or teslaundmehr. (original circuit came from teslaundmehr as far as i know)
i know this because the chinese circuit is 100% the same (only they choose for smd and to send extra parts as they know they break soon hehehe)
i think theirs runs at about 10 to 14mhz.
As one of mine 14mhz on a single irfp260n.
one of the video's i made running it with audio modulation

the fastest one i made to date is running just over 15mhz on a single irfp90n20d mosfet,
and also have been busy trying to parallel switches (but this drops the max tunable frequency for the devices to about 10mhz at most.

Gate is running in a Class E mode (so sinusoidal currents are running the gate with voltages upto 80v p2p on the gates).

i like the halfbridge design and it makes me warm building one myself too hehehe

Offline kyledellaquila

  • High Voltage Enthusiast
  • *
  • Posts: 33
  • Karma: +0/-0
    • View Profile
Re: Self Oscillating Half Bridge Wonder
« Reply #14 on: January 08, 2021, 07:13:29 AM »
Thanks Acid Byte! That Teslaundmehr is quite a talented guy.
Do you have schematics of what has reliably worked for yourself?

By the way, this came in the mail.. unfortunately, it did not come with the power supply. (36-48v at 2.5-3.5A requirement) Soon I will boot this thing up










The performance advertised:

Offline kyledellaquila

  • High Voltage Enthusiast
  • *
  • Posts: 33
  • Karma: +0/-0
    • View Profile
Re: Self Oscillating Half Bridge Wonder
« Reply #15 on: January 11, 2021, 05:36:37 AM »
I got the power supply.. pretty decent product!
The electrode gets hot reeeall fast.
https://imgur.com/SyjfI5N
https://imgur.com/1LKK2JQ
https://imgur.com/qooXvFX
https://imgur.com/W8lsmNz

Offline Acid Byte

  • High Voltage Enthusiast
  • *
  • Posts: 34
  • Karma: +1/-0
    • View Profile
Re: Self Oscillating Half Bridge Wonder
« Reply #16 on: January 13, 2021, 06:47:48 PM »

This is the schematic used as the basics.
L2 is subject to most of the tuning.

Nice yeah thats the one im talking about.. the coil made from teslaundmehrs schematic wich was made comercially available by them without consent...



To get back on the halfbridge.
I see much more performance in there whem that breakout point gets substitude by a tuned resonator (thats what im building at the moment hehe)

Offline Acid Byte

  • High Voltage Enthusiast
  • *
  • Posts: 34
  • Karma: +1/-0
    • View Profile
Re: Self Oscillating Half Bridge Wonder
« Reply #17 on: January 13, 2021, 06:52:51 PM »

Offline Weston

  • High Voltage Technician
  • ***
  • Posts: 102
  • Karma: +7/-0
    • View Profile
Re: Self Oscillating Half Bridge Wonder
« Reply #18 on: January 15, 2021, 10:20:32 AM »
This is pretty cool, it is the first time that I have seen a base fed high frequency solid state tesla coil. Looks like it works pretty well! I saw a video on facebook yesterday, not sure if it was related, but do all of these designs need to be manually "ignited" by touching the discharge point to start an arc? I suspect that with a different matching network that issue could be eliminated.

This design pretty similar to a lot of the plasma tweeter designs using vacuum tubes that are common online.

I have not done much high frequency solid state tesla coil work in years, perhaps once I have a garage again I should start working on it again. All my coils ran off a fixed oscillator to reduce interference. None of these self oscillating coils will be stable enough to stay in an ISM band.

Offline Acid Byte

  • High Voltage Enthusiast
  • *
  • Posts: 34
  • Karma: +1/-0
    • View Profile
Re: Self Oscillating Half Bridge Wonder
« Reply #19 on: January 18, 2021, 06:57:06 AM »
For more of the hv stuff find me on facebook AcidByte23

Yeah its not a very stable coil.
Would really like to go this way with a fixed crystal.
Though they start up over 50vdc on the bus.
They cannot run cw like that.
It breaks down the fet.

Ive been busy this weekend with the schematic above.
And actually got it to run at about 13mhz for now on 48vdc :)
I need some better caps for the pF range though....
(I also added a resonator wich will ultimately allow for a bigger arc at higher input voltage)

« Last Edit: January 18, 2021, 07:07:31 AM by Acid Byte »

High Voltage Forum

Re: Self Oscillating Half Bridge Wonder
« Reply #19 on: January 18, 2021, 06:57:06 AM »

 


* Recent Topics and Posts

post Re: Resonant capacitors on Chinese ZVS drivers
[Capacitor Banks]
dreamth
Today at 04:56:30 PM
post Re: Light, laser and optics - Link collection
[Light, Lasers and Optics]
dreamth
Today at 04:41:06 PM
post Re: COHERENT transformerless 81mHz amplifier schematic ?
[Light, Lasers and Optics]
dreamth
Today at 03:18:19 PM
post Re: COHERENT transformerless 81mHz amplifier schematic ?
[Light, Lasers and Optics]
Da_Stier
Today at 02:40:56 PM
post Re: COHERENT transformerless 81mHz amplifier schematic ?
[Light, Lasers and Optics]
dreamth
Today at 01:48:05 PM
post Re: COHERENT transformerless 81mHz amplifier schematic ?
[Light, Lasers and Optics]
Da_Stier
Today at 01:18:44 PM
post Re: Project: FreakyDRSSTC MK1
[Dual Resonant Solid State Tesla coils (DRSSTC)]
GrantV
Today at 11:15:01 AM
post COHERENT transformerless 81mHz amplifier schematic ?
[Light, Lasers and Optics]
dreamth
Today at 10:42:41 AM
post Interrupter frequency?
[Dual Resonant Solid State Tesla coils (DRSSTC)]
GrantV
Today at 10:08:39 AM
post Re: Baxandall converter strange output
[Transformer (Ferrite Core)]
dreamth
Today at 09:34:59 AM
post Re: TIG welder teardown. ESAB TIG Caddy 1500i.
[Electronic Circuits]
Bouaziz
Today at 09:34:05 AM
post Re: DRSSTC Performs only with 1cm Arcs - Troubleshooting
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ChrisBlis
Today at 09:30:38 AM
post Re: Baxandall converter strange output
[Transformer (Ferrite Core)]
dreamth
Today at 09:08:55 AM
post Re: Large coil experimenting with long on-times.
[Dual Resonant Solid State Tesla coils (DRSSTC)]
fh89
Today at 07:16:23 AM
post Re: DRSSTC Performs only with 1cm Arcs - Troubleshooting
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
Today at 05:08:32 AM
post Re: Project: FreakyDRSSTC MK1
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
Today at 04:47:32 AM
post Re: Baxandall converter strange output
[Transformer (Ferrite Core)]
dreamth
March 03, 2021, 11:20:38 PM
post Re: Next Gen DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
AeraCura_
March 03, 2021, 11:15:32 PM
post Re: Baxandall converter strange output
[Transformer (Ferrite Core)]
Twospoons
March 03, 2021, 10:30:40 PM
post Re: Baxandall converter strange output
[Transformer (Ferrite Core)]
dreamth
March 03, 2021, 10:03:26 PM
post Re: Need Help w/Build - Lightning Pulse Generator
[Laboratories, Equipment and Tools]
Mads Barnkob
March 03, 2021, 09:45:28 PM
post Re: Baxandall converter strange output
[Transformer (Ferrite Core)]
Twospoons
March 03, 2021, 09:44:17 PM
post First power on tests
[Dual Resonant Solid State Tesla coils (DRSSTC)]
GrantV
March 03, 2021, 06:26:23 PM
post Re: Search for opinions concerning the use or test of a yunbao / Ebay drsstc skp
[Dual Resonant Solid State Tesla coils (DRSSTC)]
GrantV
March 03, 2021, 05:54:58 PM
post Re: Baxandall converter strange output
[Transformer (Ferrite Core)]
dreamth
March 03, 2021, 03:13:30 PM
post Re: Baxandall converter strange output
[Transformer (Ferrite Core)]
dreamth
March 03, 2021, 01:18:22 PM
post Re: Baxandall converter strange output
[Transformer (Ferrite Core)]
dreamth
March 03, 2021, 12:25:52 PM
post Re: Baxandall converter strange output
[Transformer (Ferrite Core)]
dreamth
March 03, 2021, 12:24:40 PM
post Re: DRSSTC Performs only with 1cm Arcs - Troubleshooting
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ChrisBlis
March 03, 2021, 10:43:20 AM
post Re: Search for opinions concerning the use or test of a yunbao / Ebay drsstc skp
[Dual Resonant Solid State Tesla coils (DRSSTC)]
GrantV
March 03, 2021, 09:05:02 AM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic Circuits]
davekni
March 03, 2021, 05:53:33 AM
post Re: Through-hole layout of UD2.7C universal driver
[Dual Resonant Solid State Tesla coils (DRSSTC)]
profdc9
March 03, 2021, 04:22:01 AM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic Circuits]
petespaco
March 03, 2021, 04:00:14 AM
post Re: Baxandall converter strange output
[Transformer (Ferrite Core)]
davekni
March 03, 2021, 01:21:15 AM
post Re: Just a noob with some HV concerns...
[Beginners]
AstRii
March 03, 2021, 12:36:05 AM
post Re: Baxandall converter strange output
[Transformer (Ferrite Core)]
dreamth
March 03, 2021, 12:35:57 AM
post Re: Baxandall converter strange output
[Transformer (Ferrite Core)]
davekni
March 02, 2021, 11:40:16 PM
post Re: Baxandall converter strange output
[Transformer (Ferrite Core)]
dreamth
March 02, 2021, 11:29:28 PM
post Re: DRSSTC Performs only with 1cm Arcs - Troubleshooting
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 02, 2021, 10:48:04 PM
post Re: Baxandall converter strange output
[Transformer (Ferrite Core)]
davekni
March 02, 2021, 10:33:13 PM
post Re: Baxandall converter strange output
[Transformer (Ferrite Core)]
dreamth
March 02, 2021, 10:20:22 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic Circuits]
davekni
March 02, 2021, 10:18:05 PM
post Re: Search for opinions concerning the use or test of a yunbao / Ebay drsstc skp
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 02, 2021, 09:38:45 PM
post Re: Through-hole layout of UD2.7C universal driver
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Max
March 02, 2021, 08:54:33 PM
post Re: WTS [EU] Vici DM4070 LCR meter with SMD tweezers
[Sell / Buy / Trade]
Da_Stier
March 02, 2021, 08:53:31 PM
post Re: Through-hole layout of UD2.7C universal driver
[Dual Resonant Solid State Tesla coils (DRSSTC)]
profdc9
March 02, 2021, 05:04:44 PM
post Re: Search for opinions concerning the use or test of a yunbao / Ebay drsstc skp
[Dual Resonant Solid State Tesla coils (DRSSTC)]
GrantV
March 02, 2021, 03:16:25 PM
post Re: WTS [EU] Vici DM4070 LCR meter with SMD tweezers
[Sell / Buy / Trade]
AstRii
March 02, 2021, 09:41:31 AM
post Re: DRSSTC Performs only with 1cm Arcs - Troubleshooting
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ChrisBlis
March 02, 2021, 08:26:30 AM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic Circuits]
hightemp1
March 02, 2021, 07:05:01 AM

Sitemap 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 
SimplePortal 2.3.6 © 2008-2014, SimplePortal