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.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
radiotech wrote ...
The output transformer has no DC current in primary. Does the plate choke maintain the inductance with the DC current through it ? C3 seems to a standard polarized capacitor which may somewhat rectify the current and change the sound from that had with a non polarized type.
Most output transformers are designed to perform with a DC component because of the gap.
Apparently the choke won't have a problem maintaining inductance. I'm using two Varley 20H @120mA chokes, and I'll be running them at a lot less than 120mA.
C3 is actually a motor run capacitor (or similar), non polarised and at least 400V. I'll probably use 630V, if I have any, or I could series a couple of 20uF 400V ones.
One of the beautys of this circuit is that you don't need a gapped O/T, you can use one from a push-pull type amp, which are a lot more common. C3 'should' provide overcurrent protection for the OT primary too, in case of a 'mishap'. I've read about a lot of 'fried' O/T's recently
BigBad wrote ...
Long answer: yes, the extra taps have capacitance that could make a difference even if they're not carrying current because they're repeatedly raised and lowered in voltage, but no it makes no difference, because that capacitance is minute. You'd only have to worry about the extra capacitance if the pickup was running at its self resonant frequency, which likely to be in the megahertz range; and enormously beyond the audible range, and is unlikely to be driven by anything.
If the pickup is not running at that frequency, then the extra few tens of picofarads is irrelevant.
Here's a graph depicting the response from a 'similar' pickup to the one presently in the guitar. It shows resonant frequencies with various value parallel capacitors, and the turquoise line is with no additional capacitance, just the pickup's response curve. The resonant peak is between 5kh and 6kH.
I guess Hen is 'in the ballpark', the inductance of the pickup used will be less than 10H, I imagine, so it has considerably more than 20pF capacitance
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
Well, despite two bouts of pneumonia since I last posted any progress here, and loads of other stuff needing doing over the summer, and getting side tracked making jigs and templates to produce guitar bridges in batches, because of all the interest shown elsewhere on the internet where I've been researching this subject, I've now made some considerable progress with the 'test bed' that I intend to use for pickups.
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.
Question relating to electric guitar pickups and capacitance .
