dear all,
Please allow me to anounce:
http://www.tentlabs.com/Components/Tubeamp/Tubeheater/index.html
also the backgrounds might be of interest
http://www.tentlabs.com/InfoSupport/page35/files/Heatingmethods.pdf
enjoy
Guido
Please allow me to anounce:
http://www.tentlabs.com/Components/Tubeamp/Tubeheater/index.html
also the backgrounds might be of interest
http://www.tentlabs.com/InfoSupport/page35/files/Heatingmethods.pdf
enjoy
Guido
Last edited by a moderator:
Hallo Guido,
Is this the DHT supply that Triode Dick was raving about? (But could not yet reveal?)
Could you explain in layman's terms what is new about this idea?
Regards,
Bas
Is this the DHT supply that Triode Dick was raving about? (But could not yet reveal?)
Could you explain in layman's terms what is new about this idea?
Regards,
Bas
And why would you give someone else your money for something that you can make out of LM317s?
I mean, spending money makes things sounds good, but that's beside the point.
Tim
I mean, spending money makes things sounds good, but that's beside the point.
Tim
Don’t get it either. As far as I understand Guido’s page it is a voltage limited current source. Probably it will be baked when short circuited?
😉
😉
Konnichiwa,
Hmmm. I have no idea what Guido's circuit looks like, but I have been thinking about stuff like this myself. It is quite trivial to design an "electronic filter choke" which can (as a side-effect) operate as voltage regulator, but which has an impedance rising at a rate of 20db/decade (impedance multiplies by a factor 10 for each decade in frequency), whihc could have very significant levels of Impedance even at 100/120Hz.
This would certainly combine the behaviour of a CCS and a CVS with a certain transtition region at very low frequencies.
Sayonara
ultranalog said:
Hmmm. I have no idea what Guido's circuit looks like, but I have been thinking about stuff like this myself. It is quite trivial to design an "electronic filter choke" which can (as a side-effect) operate as voltage regulator, but which has an impedance rising at a rate of 20db/decade (impedance multiplies by a factor 10 for each decade in frequency), whihc could have very significant levels of Impedance even at 100/120Hz.
This would certainly combine the behaviour of a CCS and a CVS with a certain transtition region at very low frequencies.
Sayonara
That is exactly the point that has been mystified in this story.
A first order is easily achieved with an L200. Myself, I'd go for a 1 Hz, 4th order turnover or something alike.
A first order is easily achieved with an L200. Myself, I'd go for a 1 Hz, 4th order turnover or something alike.
Quite right KYW,
IMHO it is more effective to keep mains and rectifier related noise away from the DH cathode by proper LC filtering. A simple LM317 or LM338 will do then as a voltage regulator and electronic low frequency filter.
Just my 2 cents 😉
IMHO it is more effective to keep mains and rectifier related noise away from the DH cathode by proper LC filtering. A simple LM317 or LM338 will do then as a voltage regulator and electronic low frequency filter.
Just my 2 cents 😉
Bas Horneman said:
Yes, it is what excited Triode Dick...............
read the site, I put a lot of background info there !
cheers
Pjotr said:
Hi
It is not only about filtering, it is about exposing the filaments to an external impedance.
Read the presentation for background info
regards
Konnichiwa,
Well, lets look a simple theoretical circuit. We take an LM317 for simplicity, 390R/1K2 voltage set resistors for 5V and a 1,000uF coupling capacitor for the AC and a 1R sense resistor. We get a turnover of 0.5Hz and thus at 50Hz 100 times the sense resistor as Impedance (100R) and at 100Hz 200 times.
If we increase the Capacitor (and sense resistor) we can achieve quit high levels of impedance. Using standard values for a 300B Heater supply without wasting too much power we may with to use 4,700uF/16V as coupling capacitor and 2R2 as sense resistor and 1k/2k7 "set" resistors for the LM317 we get over 4KOhm impedance at 100Hz (theoretically at least) and around 4.75V DC, just ideal for a 300B.
In this design we are loosing around 3.3V in the 2R2 Resistor, which suggests a supply with a minimum of 10V prior to the whole shebang. Using a pair of 16V 4,700uF Capacitors with a little LC common mode filter (at least 2A rating) and a 9V winding plus schottky bridge we should have a nicely working supply, very low noise, high AC impedance and a 7.5 second timeconstant, giving a nicely slow start.
The resistor could be replaced with a choke, making the slope 2dn order, but it needs a pretty beefy choke, 4.7mH/2A might be usefull there as it will reduce the required voltage level and will increase a little in 100Hz impedance on the Resistor.
Anyway, some thought experiements on "electronic chokes", which would make a nice DHT supply using inexpensive off-shelf parts.
Sayonara
ultranalog said:
Well, lets look a simple theoretical circuit. We take an LM317 for simplicity, 390R/1K2 voltage set resistors for 5V and a 1,000uF coupling capacitor for the AC and a 1R sense resistor. We get a turnover of 0.5Hz and thus at 50Hz 100 times the sense resistor as Impedance (100R) and at 100Hz 200 times.
If we increase the Capacitor (and sense resistor) we can achieve quit high levels of impedance. Using standard values for a 300B Heater supply without wasting too much power we may with to use 4,700uF/16V as coupling capacitor and 2R2 as sense resistor and 1k/2k7 "set" resistors for the LM317 we get over 4KOhm impedance at 100Hz (theoretically at least) and around 4.75V DC, just ideal for a 300B.
In this design we are loosing around 3.3V in the 2R2 Resistor, which suggests a supply with a minimum of 10V prior to the whole shebang. Using a pair of 16V 4,700uF Capacitors with a little LC common mode filter (at least 2A rating) and a 9V winding plus schottky bridge we should have a nicely working supply, very low noise, high AC impedance and a 7.5 second timeconstant, giving a nicely slow start.
The resistor could be replaced with a choke, making the slope 2dn order, but it needs a pretty beefy choke, 4.7mH/2A might be usefull there as it will reduce the required voltage level and will increase a little in 100Hz impedance on the Resistor.
Anyway, some thought experiements on "electronic chokes", which would make a nice DHT supply using inexpensive off-shelf parts.
Sayonara
I did Guido!
But I simply don't know/understand how your design differs from a simple voltage reg followed by a current reg?
I am not an EE. And I think that most of your potential clients for that board will fall into that category.
Telling these kind of people to read the datasheet won't help you endear your product to them. At least I don't think so.
It's the same for your oscillators. I don't want know necessarily why they are better...but I understand that 3 ps is better than 200 ps.
But I can't understand why your filament reg is better than the vr/cr type circuit. Because I don't even know the specs of a typical LM317 vr/cr....such as I plan on building for a friend/customer (Cleo V with Doede's VR/CR. )
Regards,
Bas
Bas Horneman said:
Hi Bas,
A voltage source has a low impedance, compare with car battery, it maintains the output voltage, "regardless" of the load
A current source has a high output impedance, it maintains the output current, regardsless of the load.
My design has a high output impedance, hence does not short the differential audio current generated in the DHT
This to me is the main reason why it sounds better
And it does sound better, to many ears already
cheers
ultranalog said:
Remco,
My design filters as well, as does the traditional voltage regulator.
In addition, my design has a high output impedance, this contrary to a traditional voltage reg.
regards
ultranalog said:
If you look at the data at my site you will understand it computes
It maintains stable voltage for DC, and high output impedance for audio frequencies
The power is delivered by a voltage source. In other words, this circuit behaves like a choke.
And it's priced likewise...
And it's priced likewise...
ultranalog said:
You're free to put a choke in your designs. It is actually where I started.
It''ll be chunky, as it needs to show quite some impedance quite early in the frequency domain, and it would be fine if it is 0 ohm DC, say thick wire and loads of iron, to achieve Henries and amps, otherwise you keep adjusting the whole thing during use and the voltage source in front needs to be stable and low drop due to heat requirements.
Yes, when you've done that, you're about there. Recalculate system solution price, dealermargins included, and put it in contrast with size, weight, performance and 5 years of warrantee.
cheers