Clipping Diodes TS9. I was looking through some schematics of my favorite fuzz pedal the Ibanez TS9. Looking at the diodes in the feedback path I would think being identical this would promote 3H distortion from the symmetrical clipping. I like asymmetrical clipping and the more 2H sound so I want to change one of the diodes to something other than the 1N Will that give asymmetric clipping?
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Find More Posts by peranders. Regarding diodes. I did check a 1N in my preliminary tests and it was very quiet. I forgot to include it in the real test suite. I will measure some more LEDs and some more zener voltages when I get time, and I'll try to throw in some ordinary diodes too as well as TL Note however, that the noise of the CCS gets lumped into the noise figure, as does the amplifier noise, but these are at least the same for all DUTs.
Jackinnij, thanks for the hints but I seem to get good enough results for my purposes. I am at or very close to the theoretical limt already and I can obvoiously distinguish between components by measuring their noise. The main purpose of the experiment was to get relative noise figures to try extracting qualitative results, and that seems possible to do although the sample sizes are too small to get any real statistical significance.
Of course, if there is anybody having better equipment and is willing to repeat my experiments, that would be most welcome. I wonder if that relates to relative noise in any way. Also, I'm not trying to make work for anyone but also wonder about consitancy voltage drop and noise unit-to-unit in specific LEDs. I wonder because the device is designed to produce light and the use as a voltage reference is only incidental.
Find More Posts by sam9. Find More Posts by jackinnj. Extended report w. OK I admit it, I am crazy. I have spent many hours tonight doing more noise measurements. First, forget that update I posted using old junkbox LEDs. The results seem to have been erroneous due to a battery going flat. An extended report is attached. Although the data sample set is still quite small and doesn't warrant any statistically significant results, there seem to be certain consistencies in the results that one may perhaps dare to generalize from.
Special requirements for the current may affect the choice, though. For higher voltages up to or just below 12V, string together a suitable number of red, yellow or green LEDs.
From 12V upwards, use a zener diode or several if required. This test was not set up so it could properly find that optimum. Put the leds in the dark and measure again. LED's will generate a small voltage if there is ambient light falling on the junction actually quite useful as an opto-isolator if you face a pair of narrow-focus leds toward each other and I was thinking that the light might affect the noise figure, particularly if it is fluorescent light with it's 2x mains frequency modulation.
Maybe we should "isolate" them in some sort of black heat shrinking tube. However, given the 1. I think it is more appropriate to normalise all noise voltages to 1V zener voltages for a fair comparison. Btw maybe you can measure also a reverse biased b-e junction of a BC, at 1 mA that gives app 6.
Re: Put the leds in the dark and measure again. BB code is On. Smilies are On. Forum Rules. All times are GMT. The time now is AM. Resources saved on this page: MySQL Some noise measurements for LEDs and zener diodes. User Name. Stay logged in? Mark Forums Read. Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc. Please consider donating to help us continue to serve you. Page 4 of Thread Tools.
Have you checked power diodes also, like 1Nx or 1Nx? View Public Profile. Send a private message to peranders. Regarding diodes I did check a 1N in my preliminary tests and it was very quiet.
Send a private message to Christer. Find More Posts by Christer. Send a private message to sam9. Quote: Originally posted by peranders Curious: Do you americans have Marabou chocolate over there? Daim, Japp, etc? Send a private message to jackinnj. Attached Files. Send a private message to Circlotron. Find More Posts by Circlotron. Send a private message to Bricolo. Find More Posts by Bricolo. Send a private message to Pjotr. Find More Posts by Pjotr. Quote: Originally posted by Circlotron LED's will generate a small voltage if there is ambient light falling on the junction actually quite useful as an opto-isolator if you face a pair of narrow-focus leds toward each other and I was thinking that the light might affect the noise figure, particularly if it is fluorescent light with it's 2x mains frequency modulation.
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