Online calculators

[angelodp]

I am hoping to start a thread where we share various online calculators relating to tube amp work, with a full appreciation that a calculator is only a tool and understanding is the key.

https://www.ampbooks.com/mobile/amplifi ... alculator/

https://www.vtadiy.com/loadline-calcula ... alculator/

https://robrobinette.com/Tube_Bias_Calculator.htm

Cheers Ange

[johnnyreece]

If I may request it, is there a calculator for tremolo oscillators? I've seen several you can use as long as all three resistors and capacitors are the same value, but none where you can change any single variable.

[R.G.]

I'm not sure an online calculator can handle odd values in the typical phase shift oscillator. It's a tricky bit of math, even after the script realizes that the values are non-identical.

The math is such that if you get the component values too non-identical, the thing may not oscillate at all. The three-stage phase shift oscillator is a moderately delicate balance between too much gain (= not enough attenuation in the timing components) making it badly non-sinusoidal and too little gain (too much attenuation in the timing parts) making it not oscillate at all.

I'd use a free circuit simulator rather than an online calc. But maybe someone has solved the issue.

[dorrisant]

I'll dump some of what I have that are amp building/troubleshooting appropriate:

Tube Amp Power Transformer Current Draw Calculator - https://thesubjectmatter.com/calcptcurrent.html
Tube Bias Calculator - https://elecurls.tripod.com/biascalc2.htm
Cathode Cap Calculator - https://www.ampbooks.com/mobile/amplifi ... alculator/
Vacuum Tube Calculators - https://www.ampbooks.com/mobile/vacuum-tubes/
Preamp Tube Output Impedance Calculator - https://www.ampbooks.com/mobile/amplifi ... alculator/
LC Ripple Calculator - https://www.ampbooks.com/mobile/amplifi ... alculator/
Triode/Pentode Load Line Simulator - https://www.trioda.com/tools/triode.html
Speaker Wiring Calculator - https://www.jensentone.com/wiring-diagrams
Ohm's Law Calculator - https://ohmslawcalculator.com/ohms-law-calculator
Voltage Divider Calculator - https://ohmslawcalculator.com/voltage-d ... calculator
T-Pad/ H-Pad Calculator - https://www.nu9n.com/tpad-calculator.html
Amps to VA Converter - https://www.rapidtables.com/calc/electr ... lator.html
Load Line Calculator - https://www.vtadiy.com/loadline-calcula ... alculator/
LED Series Resistor Calculator - https://www.digikey.com/en/resources/co ... s-resistor

[e_dw1n]

There's also Ted Weber's Bias Calculator - https://www.tedweber.com/bias-calc/

And lot's on Amplified Parts:
Resistor Power Rating Calculator - https://www.amplifiedparts.com/tech-art ... wer-rating
Resistor Parallel/Series Calculator - https://www.amplifiedparts.com/tech-art ... calculator
Capacitor Parallel/Series Calculator - https://www.amplifiedparts.com/tech-art ... calculator
Biasing Tube Amplifier Calculator - https://www.amplifiedparts.com/tech-art ... calculator
Speaker Wiring Calculator - https://www.amplifiedparts.com/tech-art ... calculator
LED Parallel/Series Calculator - https://www.amplifiedparts.com/tech-art ... calculator
LED Current Limiting Resistor Calculator - https://www.amplifiedparts.com/tech-art ... g-resistor
Spring Reverb Tanks Designation Calculator - https://www.amplifiedparts.com/tech-art ... calculator
Resistor Value Calculator - https://www.amplifiedparts.com/tech-art ... lator-form
Capacitance Value Calculator for Molded Mica - https://www.amplifiedparts.com/tech-art ... calculator
Operational Amplifier (Op-Amp) Tester - https://www.amplifiedparts.com/tech-articles/op-amp
Voltage Divider - https://www.amplifiedparts.com/tech-art ... ge-divider
Capacitance Converter - https://www.amplifiedparts.com/tech-art ... erter-form
Filters - Low Pass and High Pass - https://www.amplifiedparts.com/tech-art ... -high-pass

[WhopperPlate]

This is sticky worthy

[pdf64]

Interactive VALVE DATA SHEETS and amp modelling
http://bmamps.com/ivds.html

Cathode bypass capacitor calculator
http://bmamps.com/CapCal.html

[johnnyreece]

I'm not sure an online calculator can handle odd values in the typical phase shift oscillator. It's a tricky bit of math, even after the script realizes that the values are non-identical.

The math is such that if you get the component values too non-identical, the thing may not oscillate at all. The three-stage phase shift oscillator is a moderately delicate balance between too much gain (= not enough attenuation in the timing components) making it badly non-sinusoidal and too little gain (too much attenuation in the timing parts) making it not oscillate at all.

I'd use a free circuit simulator rather than an online calc. But maybe someone has solved the issue.

I was afraid this was the answer. I've seen some circuit diagrams drawn up showing the frequency range, and assumed the folks drawing it up had a formula, but maybe they just built it and measured? On that note, would there be any issue just hooking a frequency counter up to the LED on the cathode of the oscillator tube and measuring there? I suppose I need to check the input limits on my counter, but I can't imagine there's enough to cook it.

On another side note, I did some exploring on the internet, and I did find a couple formulas here (page 5, specifically): https://dalmura.com.au/static/phase%20s ... 201941.pdf

I came up with a couple formulas that seem correct after checking that work in Excel. They only address changing a capacitor, but at least it's something! Here goes:

Set up a sheet where:
-B6 is the Resistor value (in ohms).
-E4 is the unchanged Capacitor value (in F).
-E5 is the Capacitor you want to change the value of (in F).

If you vary the capacitor off the grid, here's the formula: =1/(2*PI()*$B$6*$E$5*SQRT(($E$4/$E$5)*(5+($E$4/$E$5))))
If you vary the capacitor off the plate, here's the formula: =1/(2*PI()*$B$6*$E$5*SQRT(3*($E$4/$E$5)*(1+($E$4/$E$5))))

Obviously, if you want to place your resistor and capacitor values elsewhere in the sheet, you can just modify the formulas. This is just where they ended up when I was working it out. It seems to work. I thought it was off after looking at Merlin's page, but then I noticed he must have approximated Pi (I'm sure so that it was simple for others to memorize). That accounted for the difference. Anyhow, I hope this is useful for someone! If you find a formula that accounts for a resistor change, let me know, and I'll see if I can't clunk it up in good ol' Excel.

[pompeiisneaks]

This is sticky worthy

Stickied.

[angelodp]

One more, thanks Romberg. Modifying Taper on pots


https://www.amplifiedparts.com/tech-art ... ifications

[Gregg Hermetech]

First post, hope it's useful and hasn't already been posted!

The old Windows 'Tone Stack Calculator' also has an online version version now, semi-regularly maintained and includes lots of tone stack circuits not in the original software:

https://www.guitarscience.net/tsc/fende ... T_pot=LogA

Has me aching to add a Framus style mid scoop to my 5F1!

[LSDtigers]

You can fake custom pot tapers with this calculator. Click the Tapered Pot tab

https://www.diystompboxes.com/analogalc ... h/emh.html

[Jim Hagerman]

I have one here for inductively rectified power supplies:

http://www.hagtech.com/choke.html