Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - johnf

Pages: [1] 2 3 ... 10
1
Transformer (Ferrite Core) / Re: Green Smoke
« on: November 05, 2023, 11:35:06 PM »
Most incandescent bulbs use a little argon to help stop evaporating the tungsten filament

Has anybody tried this with multi-halide arc lamps??

2
Radio Frequency / Re: Odd Signal On VLF, Need Help Identifying Source
« on: June 28, 2022, 01:19:41 AM »
Odd indeed
Maybe ultraslow submarine comms
also if you are seeing lightning
https://vlfstanford.ku.edu.tr/research_topic_inlin/introduction-whistler-waves-magnetosphere/
is a possibilty

maybe ET's trying to communicate??

3
Solid State Tesla Coils (SSTC) / Re: Issue with IGBT gate drive
« on: May 18, 2022, 06:37:53 AM »
xana
i use one of those little propane torches to tin the copper first ie no devices anywhere near the torch
ie https://nz.rs-online.com/web/p/blow-torches/0467450?cm_mmc=NZ-PLA-DS3A-_-google-_-PLA_NZ_EN_Power_Tools_%26_Soldering_%26_Welding_Whoop-_-(NZ:Whoop!)+Blow+Torches-_-467450&matchtype=&pla-308487046968&gclid=EAIaIQobChMIjPCHg5zo9wIVQ8ORCh1sawzjEAQYASABEgI5VvD_BwE&gclsrc=aw.ds
do not buy from these people as it is very expensive.
you will also need some killed spirits of salts to use as a flux
you can make this yourself out Zinc metal and Hydrochloric acid (Muriatic acid) you make sure to have an excess of zinc ie zinc still left and no bubbling this is killed spirits of salts.
wipe the copper with this, heat with blow torch and put ordinary solder all over.
you now have tined copper that is easier to solder to

4
hopefully you made your pulleys so that they are tapered from the middle ie the middle is greater diameter than your outside edges.
doing this gives automatc belt centering much like railway wheels stay on the centre of the track.
commercial VDG's run at about 70km/Hr belt speed.
Otherwiswe nice build

5
General Chat / Re: Capacitor Esoterica
« on: May 04, 2022, 11:22:09 PM »
When i'm repairing Glassman HV PSU's I test all the multiplier stack capacitors individually at their rated DC voltage looking for leakage I have a Danbridge JP30A to do this with
https://www.danbridge.com/product_detail.php?indexs=46
without this I have never found a problem at low voltage measurements ie they measure within tolerance but at elevated voltage the leakage is way out of spec

6
Yes that amp looks like about 1.2kW of RF out maximum
I few years ago I built this for my HAM hobby in this case the BLF188XR is soldered to the heatsink to get very good thermal performance as this little FET consumes 50 volts at 55 amps and will give about 1.3 kilowatts out although I have set the ALC now to 1000 watts as this is my second fet. I forgot to put the antenna on one night and tried to put 1.3kilowatts into an open circuit and I punctured a few of the paralleled fet inside the package



7
Light, Lasers and Optics / Re: CO2 laser refurbishing
« on: March 26, 2022, 10:30:32 PM »
Twospoons
Before you attempt this there is a crown in China who will regas this tube for you
we have one of these at work and we bought a new tube from syrad approx $8000US$
The chinese want about a 1000 dolllars to recondition it

8
Transformer (Ferrite Core) / Re: Flyback winding questions
« on: March 21, 2022, 08:23:04 PM »
Coupling close to 1
or K as it is often referred to. The perfect transformer has a coupling ratio of 1 ie all the input energy is translated to the output. In practice we can get very close ie coupling ratio of 0.96 is as good as I have measured mine own designs. To measure this one measures the inductance of the primary with the secondary open circuit and again with the secondary short circuit
So coupling factor k = 1-(shorted inductance divided by the open circuit inductance)
Lets say the primary measures 10 micro-Henrys open circuit and 100 nano-Henrys short circuit  = 1-(0.1/10) = .99
The measured value of the shorted inductance is called the leakage inductance
As coupling factor goes down the leakage inductance goes up which with flybacks manifests itself as high reflectance from the secondary to the primary and this energy gets absorbed by the snubbers on the switching device with out the snubbers your switching device will see much higher voltages than your DC bus

9
Transformer (Iron Core) / Re: Pole Pig Refill
« on: March 13, 2022, 11:16:45 PM »
Use Shell Diala S5
do not mix other oils in unless replacing it all

10
Voltage Multipliers / Re: Flyback ratio question
« on: February 18, 2022, 10:43:49 PM »
Not quite
yes the turns ratio comes into it but also the leakage inductance and a few other things like winding capacitance
so you will tend to get a higher voltage than the turns ratio suggests

11
General Chat / Re: Flaky DOCSIS 3.0 modem power supply
« on: February 18, 2022, 04:15:51 AM »
Steve
Internet modem supplies are the bane of all amateur radio operators
Cheap
Nasty
and noisy
and thats when they are new
they go downhill from there.
Most hams try to find a 50/60Hz transformer version to replace them trouble is of course your neighbors with the SWPS version

12
Voltage Multipliers / Re: Litz Wire
« on: February 07, 2022, 03:28:13 AM »
No picture
No actual core spec or pic with ruler
No number of primary turns
No measured inductance
No measured leakage inductance
Around 20kHz +-?

Probably your Turbo Encabulator

13
Solid State Tesla Coils (SSTC) / Re: GDT Testing
« on: January 22, 2022, 05:27:37 AM »
If you have two identical cores make two and put them back to back
then run some power at various frequencies through them, losses are exacerbated by a factor of two so it should be easy to see

14
Capacitor Banks / Re: "Exploding" water
« on: November 26, 2021, 09:17:07 AM »
Steve
we used to do this to generate very big compression waves in sea water for geotectonic sonar
used 500uF charged to to 15kV and two electrodes about half a meter apart about 100 meters down in the sea. water got ionised between electrodes
resulting bang then gave us a look at the underlying strata on the sea floor (oil exploration). Repetition rate about 10 hz
triggered spark gap fired the charge down the coax cables to the electrodes.
Used to test it in the university carpark in a trough of sea water --better than any buyable fire cracker - needed very good ear protection to get near

15
Voltage Multipliers / Re: Resistance to protect flybacks, etc.
« on: October 15, 2021, 07:46:28 AM »
Parallel 10-1000 meg-ohms per kv depending on circuit topology
as for series this depends on power of the supply but I tend for a minimum of 1000% of the max current ie a supply of 100kV 100mA you would use a 100k ohms supply impedance = 12 meg ohm.
More if you want to protect your supply or less if you are adventurous

16
Vacuum Tube Tesla Coils (VTTC) / Re: Hi! 811 A tesa coil
« on: October 01, 2021, 08:50:32 AM »
Yes I was wondering why the grid RF bypass cap had to have such a high voltage rating

17
Spark Gap Tesla Coils (SGTC) / Re: Keep blowing capacitors
« on: September 29, 2021, 07:39:27 AM »
I tried to "Modify" my post but the board refused to act!!!

I meant to say that tuned circuit "Q" is made better by increasing capacitance with reducing inductance ie "Q" is proportional to "C" in a tuned circuit

18
Spark Gap Tesla Coils (SGTC) / Re: Keep blowing capacitors
« on: September 29, 2021, 07:35:03 AM »
Your last answer has all the clues
you had to reduce primary turns and increase the capacitance to get good sparks

ie "Q" was not enough
 "Q" = high circulating currents and if these cannot be got the voltage rises

you need pulse rated capacitors that have enough voltage stand off and current capacity

19
Electronic Circuits / Re: Counterfit Parts
« on: September 29, 2021, 06:24:54 AM »
All they need to do is buy cheap lesser spec'ed overrun parts from a legit maker and remove the markings and put new laser marked part number on from an expensive part.
Measuring Gate capacitance is easy for Fets not so reassuring for IGBTs of course.
Once upon a time I worked for a very large electronics company and one line of products we made were 2 way radios (RT's) for trucking firms Taxis and law enforcement for worldwide sale.
We had several of our designs copied in an Asian country and sold at much cheaper prices worldwide. We then started making fake parts ourselves this involved a cmos 4013 all the markings taken off legs then bent around the other way and circuitry put around it to make it look like a well known Switch mode controller IC. WEe marked these ourselves with a commercial inkjet printer that used uv cure. You guessed it our design was copied and they were having terrible trouble making it go. It would not work with the unitrode part, they asked us for spares and we sold them a few hundred parts for many many terns of dollars each. Our vendor mark on our fake parts looked like the Signetics logo who never made items like tis

20
General Chat / Re: Large Rectifier Tube
« on: September 17, 2021, 10:06:53 AM »
You might want to consider it a room warmer (not heater) with that filament power
I've got a glass water cooled anode triode that has a kilowatt heater that I might do something similar to comes out of a 7.5kilowatt induction heater

Pages: [1] 2 3 ... 10

* Recent Topics and Posts

post Re: Re-chargeable 1.5 volt lithium ion AAA batteries
[General Chat]
MRMILSTAR
Today at 04:47:35 AM
post Re: Re-chargeable 1.5 volt lithium ion AAA batteries
[General Chat]
davekni
Today at 03:59:27 AM
post Re: Kaizer VTTC 1
[Vacuum Tube Tesla Coils (VTTC)]
MRMILSTAR
March 28, 2024, 09:15:11 PM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
Alberto
March 28, 2024, 01:01:12 PM
post Re: Big Coil Build Log
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
March 28, 2024, 05:47:34 AM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
davekni
March 28, 2024, 04:45:07 AM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
MRMILSTAR
March 28, 2024, 04:18:27 AM
post Push Pull VTTC
[Vacuum Tube Tesla Coils (VTTC)]
janno288
March 28, 2024, 01:10:08 AM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
Alberto
March 27, 2024, 10:54:52 PM
post Re: CM400 Induction Heater
[Electronic Circuits]
markus
March 27, 2024, 11:53:42 AM
post Re: OCD Triggering Early + Low Output
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 27, 2024, 05:14:36 AM
post Re: Is the UD2.7C under voltage lock out basically worthless?
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 27, 2024, 04:47:48 AM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 27, 2024, 04:41:59 AM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
March 27, 2024, 12:04:34 AM
post Re: Super flat QCW simulation (does this look reasonable?)
[Dual Resonant Solid State Tesla coils (DRSSTC)]
toooldforthis
March 26, 2024, 11:08:14 PM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 26, 2024, 11:07:20 PM
post Re: Is the UD2.7C under voltage lock out basically worthless?
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 26, 2024, 10:46:29 PM
post OCD Triggering Early + Low Output
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Saattvik24
March 26, 2024, 09:03:43 PM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
March 26, 2024, 08:46:59 PM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
March 26, 2024, 05:02:18 PM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
March 26, 2024, 03:16:03 PM
post Re: CM400 Induction Heater
[Electronic Circuits]
Anders Mikkelsen
March 26, 2024, 01:41:49 PM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 26, 2024, 04:48:22 AM
post Re: Re-chargeable 1.5 volt lithium ion AAA batteries
[General Chat]
MRMILSTAR
March 26, 2024, 04:16:37 AM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 26, 2024, 04:16:24 AM
post Re: Smoke Screen Machine Protect 950 XP - Teardown of a Smoke Cannon!
[Electronic Circuits]
davekni
March 26, 2024, 04:13:02 AM
post Re: CM400 Induction Heater
[Electronic Circuits]
davekni
March 26, 2024, 04:00:43 AM
post Re: Re-chargeable 1.5 volt lithium ion AAA batteries
[General Chat]
davekni
March 26, 2024, 03:19:18 AM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
thedoc298
March 26, 2024, 01:50:42 AM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
March 25, 2024, 08:05:02 PM
post Re: Smoke Screen Machine Protect 950 XP - Teardown of a Smoke Cannon!
[Electronic Circuits]
Mads Barnkob
March 25, 2024, 07:41:29 PM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
March 25, 2024, 06:45:46 PM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
March 25, 2024, 05:44:25 PM
post Re: CM400 Induction Heater
[Electronic Circuits]
Anders Mikkelsen
March 25, 2024, 04:47:17 PM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
March 25, 2024, 04:27:22 PM
post Re-chargeable 1.5 volt lithium ion AAA batteries
[General Chat]
MRMILSTAR
March 25, 2024, 03:57:34 PM
post Re: CM400 Induction Heater
[Electronic Circuits]
markus
March 25, 2024, 02:06:41 PM
post Re: Odd MOSFET Driver Behavior
[Solid State Tesla Coils (SSTC)]
KrisPringle
March 25, 2024, 04:43:25 AM
post Re: Odd MOSFET Driver Behavior
[Solid State Tesla Coils (SSTC)]
davekni
March 25, 2024, 02:39:40 AM
post Re: Odd MOSFET Driver Behavior
[Solid State Tesla Coils (SSTC)]
KrisPringle
March 25, 2024, 12:47:09 AM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
Alberto
March 24, 2024, 07:36:32 PM
post Re: My completed 14-stage Cockroft-Walton voltage multiplier
[Voltage Multipliers]
Alberto
March 24, 2024, 07:27:24 PM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
MRMILSTAR
March 24, 2024, 04:25:23 AM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
Alberto
March 23, 2024, 10:47:35 PM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
MRMILSTAR
March 23, 2024, 09:30:21 PM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
Alberto
March 23, 2024, 04:34:31 PM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
MRMILSTAR
March 23, 2024, 03:04:25 PM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
Alberto
March 23, 2024, 01:38:34 PM
post Re: capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
MRMILSTAR
March 23, 2024, 04:20:03 AM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
davekni
March 23, 2024, 12:54:30 AM
post Re: Smoke Screen Machine Protect 950 XP - Teardown of a Smoke Cannon!
[Electronic Circuits]
davekni
March 23, 2024, 12:05:57 AM
post capacitor and diodes. Voltage values for a CW
[Voltage Multipliers]
Alberto
March 22, 2024, 11:45:03 PM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
OmGigaTron
March 22, 2024, 11:30:09 PM
post Smoke Screen Machine Protect 950 XP - Teardown of a Smoke Cannon!
[Electronic Circuits]
Mads Barnkob
March 22, 2024, 10:20:35 PM
post Re: Where's all this voltage coming from?
[Spark Gap Tesla Coils (SGTC)]
Benbmw
March 22, 2024, 09:21:13 PM
post Re: What actually kills MOSFETs?
[Beginners]
AstRii
March 22, 2024, 03:37:11 PM
post What actually kills MOSFETs?
[Beginners]
FPS
March 22, 2024, 05:09:20 AM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 22, 2024, 03:57:54 AM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 22, 2024, 02:59:25 AM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 21, 2024, 06:31:42 PM
post Re: 2x Panasonic Inverter Microwaves - what to salvage, dangers?
[General Chat]
rikkitikkitavi
March 21, 2024, 03:08:01 PM
post Re: [WTS] IGBT, Ferrite, Capacitors, Tools, PSU, Industrial components and parts
[Sell / Buy / Trade]
Mads Barnkob
March 21, 2024, 01:37:32 PM
post Re: Difference between these transformers
[Transformer (Ferrite Core)]
Alberto
March 21, 2024, 11:42:07 AM
post Re: Phase Lead Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 21, 2024, 04:09:14 AM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 21, 2024, 02:15:31 AM
post My Homemade Structural Analysis X-Ray Machine
[X-ray]
Luca c.
March 21, 2024, 01:35:40 AM
post Re: Phase Lead Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Saattvik24
March 20, 2024, 10:40:00 PM
post Re: Difference between these transformers
[Transformer (Ferrite Core)]
Mads Barnkob
March 20, 2024, 08:03:41 PM
post Re: 2x Panasonic Inverter Microwaves - what to salvage, dangers?
[General Chat]
Mads Barnkob
March 20, 2024, 07:51:57 PM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
March 20, 2024, 10:39:47 AM
post Re: Phase Lead Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 20, 2024, 04:09:59 AM
post Re: 160mm DRSSTC II project | Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 20, 2024, 01:13:23 AM
post Re: Phase Lead Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Keybored
March 20, 2024, 12:45:16 AM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
March 20, 2024, 12:30:30 AM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 19, 2024, 11:12:24 PM
post Re: 160mm DRSSTC II project | Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Late
March 19, 2024, 09:47:49 PM
post Re: 160mm DRSSTC II project | Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Late
March 19, 2024, 09:44:19 PM
post Phase Lead Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Saattvik24
March 19, 2024, 06:52:09 PM
post Re: 160mm DRSSTC II project | Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
March 19, 2024, 05:02:44 PM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
Mads Barnkob
March 19, 2024, 05:01:41 PM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
March 19, 2024, 04:31:02 PM
post Re: 160mm DRSSTC II project | Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
March 19, 2024, 03:59:54 PM
post Re: Benjamin's DRSSTC 2 in progress
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
March 19, 2024, 06:41:39 AM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
davekni
March 19, 2024, 04:05:49 AM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
OmGigaTron
March 18, 2024, 09:08:35 PM
post Re: Can I Trust This Super Cheap Site?
[General Chat]
2020-Man
March 18, 2024, 09:07:35 PM
post Re: Can I Trust This Super Cheap Site?
[General Chat]
Twospoons
March 18, 2024, 08:57:06 PM
post Re: Can I Trust This Super Cheap Site?
[General Chat]
MRMILSTAR
March 18, 2024, 03:51:33 PM
post Re: 160mm DRSSTC II project | Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Late
March 18, 2024, 02:59:46 PM
post Re: 160mm DRSSTC II project | Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Late
March 18, 2024, 02:33:25 PM
post Can I Trust This Super Cheap Site?
[General Chat]
2020-Man
March 18, 2024, 11:02:12 AM
post Re: Where's all this voltage coming from?
[Spark Gap Tesla Coils (SGTC)]
Twospoons
March 18, 2024, 02:36:11 AM
post Re: Best forum for vacuum tube amplifiers?
[General Chat]
Mads Barnkob
March 17, 2024, 07:42:55 PM
post Re: 2x Panasonic Inverter Microwaves - what to salvage, dangers?
[General Chat]
Michelle_
March 17, 2024, 04:15:14 PM
post Re: 2x Panasonic Inverter Microwaves - what to salvage, dangers?
[General Chat]
Michelle_
March 17, 2024, 05:05:04 AM
post Re: Where's all this voltage coming from?
[Spark Gap Tesla Coils (SGTC)]
davekni
March 17, 2024, 04:50:51 AM
post Re: 2x Panasonic Inverter Microwaves - what to salvage, dangers?
[General Chat]
Twospoons
March 17, 2024, 04:45:17 AM
post 2x Panasonic Inverter Microwaves - what to salvage, dangers?
[General Chat]
Michelle_
March 17, 2024, 04:17:51 AM
post Where's all this voltage coming from?
[Spark Gap Tesla Coils (SGTC)]
Terry
March 17, 2024, 01:29:32 AM
post Re: DRSSTC Questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
March 17, 2024, 12:33:06 AM

SimplePortal 2.3.6 © 2008-2014, SimplePortal