Welcome
Username or Email:

Password:


Missing Code




[ ]
[ ]
Online
  • Guests: 18
  • Members: 0
  • Newest Member: omjtest
  • Most ever online: 396
    Guests: 396, Members: 0 on 12 Jan : 12:51
Members Birthdays:
All today's birthdays', congrats!
Plasmana (31)
porkcake (52)


Next birthdays
03/20 Paul I (37)
03/20 Sigurthr (38)
03/21 Dr Who (40)
Contact
If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.


Special Thanks To:
  • Aaron Holmes
  • Aaron Wheeler
  • Adam Horden
  • Alan Scrimgeour
  • Andre
  • Andrew Haynes
  • Anonymous000
  • asabase
  • Austin Weil
  • barney
  • Barry
  • Bert Hickman
  • Bill Kukowski
  • Blitzorn
  • Brandon Paradelas
  • Bruce Bowling
  • BubeeMike
  • Byong Park
  • Cesiumsponge
  • Chris F.
  • Chris Hooper
  • Corey Worthington
  • Derek Woodroffe
  • Dalus
  • Dan Strother
  • Daniel Davis
  • Daniel Uhrenholt
  • datasheetarchive
  • Dave Billington
  • Dave Marshall
  • David F.
  • Dennis Rogers
  • drelectrix
  • Dr. John Gudenas
  • Dr. Spark
  • E.TexasTesla
  • eastvoltresearch
  • Eirik Taylor
  • Erik Dyakov
  • Erlend^SE
  • Finn Hammer
  • Firebug24k
  • GalliumMan
  • Gary Peterson
  • George Slade
  • GhostNull
  • Gordon Mcknight
  • Graham Armitage
  • Grant
  • GreySoul
  • Henry H
  • IamSmooth
  • In memory of Leo Powning
  • Jacob Cash
  • James Howells
  • James Pawson
  • Jeff Greenfield
  • Jeff Thomas
  • Jesse Frost
  • Jim Mitchell
  • jlr134
  • Joe Mastroianni
  • John Forcina
  • John Oberg
  • John Willcutt
  • Jon Newcomb
  • klugesmith
  • Leslie Wright
  • Lutz Hoffman
  • Mads Barnkob
  • Martin King
  • Mats Karlsson
  • Matt Gibson
  • Matthew Guidry
  • mbd
  • Michael D'Angelo
  • Mikkel
  • mileswaldron
  • mister_rf
  • Neil Foster
  • Nick de Smith
  • Nick Soroka
  • nicklenorp
  • Nik
  • Norman Stanley
  • Patrick Coleman
  • Paul Brodie
  • Paul Jordan
  • Paul Montgomery
  • Ped
  • Peter Krogen
  • Peter Terren
  • PhilGood
  • Richard Feldman
  • Robert Bush
  • Royce Bailey
  • Scott Fusare
  • Scott Newman
  • smiffy
  • Stella
  • Steven Busic
  • Steve Conner
  • Steve Jones
  • Steve Ward
  • Sulaiman
  • Thomas Coyle
  • Thomas A. Wallace
  • Thomas W
  • Timo
  • Torch
  • Ulf Jonsson
  • vasil
  • Vaxian
  • vladi mazzilli
  • wastehl
  • Weston
  • William Kim
  • William N.
  • William Stehl
  • Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Western Winter Teslathon 2011
Hello all,

I will be in attendance today at the Western Winter Teslathon 2011. Details here: http://www.drsparksite.com/teslathon2011.htm

Hope to see some of my fellow 4hvers at the thon, and looking forward to having a great time. There will also be a live feed at http://www.teslauniverse.com/stream.html. Check there, and http://www.teslauniverse.com/ for updates. I'll be posting a full report and lots of pictures soon! I'm also creating a thread for myself and others to blog about the thon, here: Link2

Apologies for not getting a post up about this sooner, but Dr Spark asked me not to promote the event on 4hv.org.
Posted by Chris Russell on Saturday 05 March 2011 - 17:09:43 | Comments are turned off for this item | printer friendly create pdf of this news item
Site Restored from Backup
4hv.org was restored from a backup early this morning, due to the catastrophic failure of the server's primary hard drive. All data on the drive was lost. Unfortunately, as Murphy's Laws would seem to dictate, the hard drive failed while the backup was at its greatest possible age. This means the site has effectively reverted one week into the past.

I know this is frustrating for everyone. To ensure it cannot happen again, I've purchased an off-site nightly backup solution for 4hv.org. The expense is unfortunate, but I want to make sure this is the last time that something like this can happen.

If you've made any posts, created any threads, or sent any PMs over the last week, please feel free to recreate them.

If you stopped by Finn's Project Thread for Thumper, or even if you haven't, please drop by and let him know what you think of his project. He had collected a lot of nice praise and interest over the last week, and he's really earned it.

Finally, as an incentive to get things going again, I'd like to announce a small contest. Anyone who makes an interesting, thought-provoking, or high quality post over the next week will be entered into a drawing to win a 4hv.org t-shirt. The new shirt will incorporate elements of the upcoming site re-design, so the winner gets a first sneak-peek at more of the new site.
Posted by Chris Russell on Thursday 24 June 2010 - 19:47:49 | Comments are turned off for this item | printer friendly create pdf of this news item
Featured Project
This featured project goes out to a long-time 4hv.org members who has been pouring his heart and soul into an amazing project for over a year now. For those who haven't heard or seen, Finn Hammer, with help from Daniel Uhrenholt, has been doing some really incredible work on his latest coil, Thumper. His design is innovative to say the least, and he's really gone out of his way to not only create a work of art, but to document it thoroughly. He has posted images, videos, schematics, layouts, and extensive commentary. Here's just a small sample of images from his project thread:

2F1241285575 205 FT68820 Burden 2F1242335695 205 FT68820 Board2 2F1243709883 205 FT68820 Rising 2F1244580533 205 FT68820 Brucke1 2F1245963051 205 FT68820 Cm600motor1 Front 2F1269796754 205 FT68820 Assem3 2F1273775407 205 FT68820 Sanity1 2F1275848266 205 FT6000 Litle People 2F1275858866 205 FT6000 Thumper

The end result is quite possibly the world's largest DRSSTC coil, but that's not even the best part. It's the first DRSSTC coil with a primary tap adjustable at run time. That's right, it can be tuned in real-time:



This also marks the debut of the Predikter circuitry, which may just change the way a lot of people will be coiling in the years to come.

If you haven't had a chance to stop by the project thread, please do so and let Finn know what you think.

Update: Thumper has been featured on Hackaday. Congrats, Finn!
Posted by Chris Russell on Thursday 17 June 2010 - 01:05:14 | Comments are turned off for this item | printer friendly create pdf of this news item
Junk Box Update
The 4hv.org Community Junk Box is now ready! Visit http://wiki.4hv.org/index.php/4hv.org_Community_Junk_Box to see what's currently in the junk box, and learn how to participate.

As I'm sure most of you know, the 4hv.org Migratory Junk Box was lost along with most of its contents. The contents that weren't lost are apparently not going to be returned. I've been unable to even secure the return of the log book -- the person who currently has it has gone completely silent. We've made some changes to the way the junk box will be handled from here on out, to ensure a devastating loss like this cannot happen again. The junk box is now operated from a central location, saving postage and allowing the box's size to grow without restriction. It's just getting off the ground; I hope to add much more in the weeks and months ahead.

Here is a small sample of the junk available right now:

Schottky Rollerinductor Plasticcap Doorknob2 Igbtbrick

All are welcome to participate in the junk box. However, postage for those outside of North America may be high for larger items. If there is anyone who is interested in running a similar, centralized junk repository in another geographical region, please contact me. At the very least, it would be helpful to have additional repositories in the UK and EU. Our Australian members may also be able to generate enough interest to sustain a sizable junk box. If there's enough interest, I'm also looking into creating a "free stuff" board, so that members who'd like to give away items but don't want to participate in a junk box can also list what they have up for grabs. Again, please contact me if that's of interest -- the more feedback I receive, the better.
Posted by Chris Russell on Tuesday 11 May 2010 - 23:32:11 | Comments are turned off for this item | printer friendly create pdf of this news item
Featured Project
This featured project was called to my attention recently. IamSmooth put a lot of hard work into his Residential Grid Tied Wind Turbine. If you haven't seen it yet, take a look. Here's a preview:


Basically, the project consists of building a tower that is easy to raise and lower; building the generator; carving the blades to match the generator; running the power to the grid with the appropriate disconnects and power diversion features. Most people charge batteries with wind energy. This requires a compromise in power output. This is because wind energy goes up with the cube of speed. Low winds have little energy and high winds have enormous energy. One has to determine if they want to harness more consistent lower energy winds, or capture infrequent high energy winds. This is because the stator and blades need to be matched. A stator that can handle high power levels in high winds will stall out the blades in lower winds. If the blades are too large for the stator they will run away in high winds and fry the stator, or cause the turbine to self destruct from high RPM. I chose to feed power to the grid, allowing the inverter to draw off the appropriate amount of power at various wind speeds.

2F1245523192 190 FT0 Axial 2F1245523395 190 FT0 Assembly Cuttingback 2F1245523754 190 FT0 Woundcoil


Read More...

Posted by Chris Russell on Saturday 23 January 2010 - 20:55:14 | Comments are turned off for this item | printer friendly create pdf of this news item
Site Restored
Due to a server move, the site was accidentally reverted this morning to the way it appeared on Sunday afternoon, EST. I've now restored the missing posts from Monday. Any posts made in the early hours of today, Tuesday, have vanished, however. Please feel free to re-post anything that was missing.

Apologies for the interruption!
Posted by Chris Russell on Tuesday 10 November 2009 - 15:11:39 | Comments are turned off for this item | printer friendly create pdf of this news item
New Site, Featured Projects
This is just a quick update to let everyone know that due to faster-than-expected progress on the new site, featured projects will be on hold for a little while. However, just to keep things interesting, here's a classic project from early 2007 that you may have missed. Behold, Marko's DRSSTC v1.1:

2F1168461451 89 FT6000 P1010006 2F1171155315 89 FT1630 P1010074 2F1181339757 89 FT1630 A 5

Stay tuned for updates regarding the new site's rollout, and feel free to drop by Marko's thread.
Posted by Chris Russell on Sunday 11 October 2009 - 03:27:32 | Comments are turned off for this item | printer friendly create pdf of this news item
Registrations Re-Opened, Donations Address Changed
Hello all,

This is just a quick update to make everyone aware of what's going on with 4hv.org. There are some important things that I'd like to cover, so bear with me.

First, I apologize for getting behind on featured projects. I intend to restart this feature and keep it going every other Friday, starting August 7th. If you have any projects in mind, please feel free to drop me a PM or put a note in the suggestion box forum. Otherwise, I will continue to select ones that I think will be interesting to the most people.

Second, registrations have been closed for a while. This was partly due to some database tests I was performing with regards to getting existing user profiles integrated into the new site, and partly due to a large flood of users registering and not doing their part to follow the rules or keep the board clear of clutter. Registrations are now re-opened. If you've signed up and haven't received a verification email, please sign up again. Remember to observe the rules of the site; I don't want to have to step up to things like warnings and bans.

Third, the paypal address for donations has changed, both to keep things secure, and to keep things simpler. Donations will now go to **link**, the same address used for collecting webhosting payments. So, if you decide to make a donation, which I always appreciate, don't be alarmed if the address has changed. Note also that I currently bold and highlight the names of people who have donated recently. As always, if you'd like to donate in someone else's name, or would like your name displayed differently, send me a PM or include a note with the donation.

Fourth, I know times are tough. I am extremely grateful that even with the economic downturn, people have continued to donate when they are able. This really means a lot to me, and even though I know it isn't always visible, it makes a big difference in how much time I'm able to spend working on the site, even if it just means testing a script or a database link for the upcoming new site. As a way of saying thank you to everyone who has donated, if anyone whose name appears on the donation list would like a free @4hv.org email address for life, just let me know via PM and I will gladly set it up: email accounts can be accessed via IMAP/POP3 clients, or through a webmail interface.

Last, but not least, as many of you may be aware, I'm moving to northwestern Pennsylvania in August. I will no longer be living in Maine. Both money and time will be tight during the relocation, but I think everyone will be happy with the end result; starting in September, I'll be able to set aside much more time for 4hv.org. That means the long-awaited changes won't be far off, which is good news for everyone concerned. Fortunately, much of the behind-the-scenes work is complete. Exciting times lie ahead!

-Chris
Posted by Chris Russell on Friday 31 July 2009 - 16:37:22 | Comments are turned off for this item | printer friendly create pdf of this news item
Featured Project
This week, we have another gem from the archives: WaveRider's low power 433 MHz BPSK data transmission system. WaveRider single-handedly designed and implemented a complete data transmission system, using a highly efficient method of modulation. He's also obviously gone through extreme pains to document the entire project thoroughly. This is a special treat for those of us who enjoy telecommunications as a hobby.

Feel free to stop by the thread and let WaveRider know what you think. And, as always, feel free to send me a PM with suggestions for next week's featured project.

WaveRider wrote ...

It's been a while since I have done a radio project. So, I thought I would experiment with data transmission using BPSK (Binary Phase Shift Keying) on the 433 MHz European ISM band.

What's so special about BPSK?
Most commercial systems seem to use frequency shift keying (FSK) or some form of on-off keying (OOK). I wanted to explore the possibilities of constructing a simple system for binary phase shift keying (BPSK). Binary phase shift keying is a form of modulation that is very "power efficient." This means that to achieve a certain bit error rate, the required signal to noise ratio is lower than that required by, e.g., frequency shift keying or on-off keying. BPSK (or QPSK) is often the modulation mode of choice for deep space probes where power consumption must be minimised and signal path losses are enormous. See graphic (taken from Link2 ) for comparison of error rates....

1148907547 29 FT1630 Bpskber


Why 433.92 MHz?
Besides sitting in the middle of the 433MHz European ISM (industrial, scientific and medical) band, it is also in the amateur 70cm band, so parts were easy to get and it can be modified to operate under amateur radio rules. For those in the US, I think this band also falls under Part 15 of FCC regulations for low-power communications devices. Also, the local oscillators use of-the-shelf SAW resonators instead of a PLL synthesizer. This simplifies the design greatly (at the expense of having to operate on a fixed frequency).

What will the transmitter power be?
Operating below 10mW in this band is permitted without a license. I plan to limit the emissions to somewhat less than this. Many garage door openers and automotive key fobs seem to operate in this band (altho' at much below this power level). Hopefully this won't mean intolerable interference in my experiments!

First step: The receiver design
Since the receiver design is more challenging than the transmitter, I started off there. Here is a block diagram of my proposed receiver.


1148907084 29 FT1630 Bpskrx


I am basing the system around the Philips SA639 RF/IF subsystem chip, which is really designed for FSK systems, using a 10.7MHz IF. I managed to find a 500kHz bandwidth ceramic IF filter which should allow upwards of 384kbit/sec communications. BPSK demodulation is not as easy as FSK. Basically, we need to add a carrier regeneration system (a PLL) for demodulating the BPSK signal coherently. I do this with a simple "squaring loop" which doubles the IF carrier frequency. A NE564 PLL/VCO system is the heart of this.

The system
The received signal enters the system (as you would expect tongue ) at the antenna input. A low noise amplifier, based on the BFR540 NPN transistor amplifies the antenna signal. I was a bit torn about whether to put the microstrip-based band/image-reject filter before the low noise amplifier. If I put the filter before the amplifier, the filter insertion loss will kill the noise figure of the system. However, putting the filter after the amplifier increases the chances of amplifier overload by strong out-of-band signals. I opted for putting the filter after the amplifier. I will rely on the antenna system to reduce out-of-band signals. Plus, the BFR540 amplifier as I have designed it should be able to withstand -20dBm on the input terminals without saturating.

The next stage is the downconverting mixer. I found a SAW resonator for 423.22MHz which is exactly 10.7MHz away from 433.92MHz. Hence, the local oscillator (based on a BFR92 transistor) fed to the mixer (part of the SA639 chip) downconverts perfectly to 10.7MHz. The ceramic IF filter passes a sharply defined 500kHz channel to the
first IF amp and limiter.

At this point, we split off the signal to the second mixer as well as a push-push active frequency doubler. The output of the doubler is passed through a 21.4MHz (second harmonic) bandpass filter (with a band-stop notch at 10.7MHz) to the PLL carrier regeneration circuit. The 21.4MHz signal is divided by 2 using a flip-flop. After a phase correction and level adjusting circuit, the regenerated carrier is fed to the final mixer, where it is mixed with the original amplitude limited IF signal. The output will be the original BPSK digital data signal (a 250kHz low-pass filter on the output remives any residual RF). A schmitt trigger squares up the output and produces a TTL compatible signal.

I am hoping for a BER at 384kbit/sec of under 10e-6 with -106dBm input at the antenna terminals (in the absence of other interfering transmitters).


Additional Pictures:

1148986277 29 FT1630 Pcbfoto1small1150378092 29 FT1630 Dsc012211150380009 29 FT1630 Rxlo 1150378092 29 FT1630 Dsc01223 1150378092 29 FT1630 Dsc01224 2F1151053840 29 FT1630 Bpskschem 2F1151052526 29 FT1630 Dsc01228 2F1151052526 29 FT1630 Dsc01231 2F1151052526 29 FT1630 Dsc01232 2F1151052526 29 FT1630 Dsc01230 2F1151494769 29 FT1630 Carrierrecovery 2F1151494544 29 FT1630 Dsc01237 2F1151494544 29 FT1630 Dsc01240 2F1151494544 29 FT1630 Dsc01241 2F1151494544 29 FT1630 Dsc01243 2F1151494544 29 FT1630 Dsc01245 2F1151587014 29 FT1630 Dsc01246 2F1156945262 29 FT1630 Carrierrecovery Ver2 2F1158831002 29 FT1630 Dsc01500small
Posted by Chris Russell on Friday 29 May 2009 - 19:36:16 | Comments are turned off for this item | printer friendly create pdf of this news item
Featured Project
This week, some suggested that I dig something up from the older threads. So, I present to you, Dr. Spark's Small Bi-polar SSTC, a project from November of 2006. Dr. Spark's meticulous construction and careful attention to detail here does not disappoint. Please feel free to stop by the thread and let Dr. Spark know what you think. I believe some of you have now witnessed this coil operating in person.

If you have any feedback or suggestions for a project that you think deserves some recognition, please let me know. There are some really great current projects on the projects board, as well as quite a few on the following pages that have probably been overlooked.

Dr. Spark wrote ...

Good day great coilers,

I am now madly in love with solid state Bi_Polar coils. How little power they take and how fast they can respond is incredible Link2 ! Demo Lady Red for DC Cox this weekend and he was grinning big time. wink

I have 1.2 months left before the W.W.T. Link2 so thought I could squeeze one more project in for demo at the Thon. A small SSTC Bi-Polar with a surprise feature. So pics tonight are the starting project, coil will be all plexy with UV LED’s. Will update with pics but this will be the fastest built coil I have done in many, many years….. Have a goal to meet, so off the computer and back in the garage… suprised

Cheers,
Ch_r


Pictures:


2F1164083002 290 FT0 Bpsstc2 2F1164641678 290 FT18200 Sstcbp2 2F1165367135 290 FT18200 Sstcbp102 2F1165545556 290 FT18200 Sstc Bpbase 2F1166651986 290 FT18200 Blueone 2F1196057248 290 FT18200 Twostack2 2F1196057248 290 FT18200 Finalstack1 2F1196057248 290 FT18200 Finalstack3x
Posted by Chris Russell on Thursday 21 May 2009 - 15:18:12 | Comments are turned off for this item | printer friendly create pdf of this news item
Go to page  1 2 3 4 5 
 
Legal Information
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.