Search found 13 matches

by cyrdun
Sun Apr 15, 2018 8:15 am
Forum: Music Tech DIY
Topic: matching transistors - DIY
Replies: 481
Views: 78033

Don't they settle after a while? As they conduct current the transistors will heat up, presumably not quite at the same rate if they are not perfectly matched and at an identical temperature in the beginning. But it should settle. Thanks for your answer. However I've left the circuit powered for tw...
by cyrdun
Sat Apr 14, 2018 12:01 pm
Forum: Music Tech DIY
Topic: matching transistors - DIY
Replies: 481
Views: 78033

Hi I'm using Dave Jones' tweak on Ian Fritz circuit. Hopefully I'm using it the right way now :D. Still I have readings that don't make any sense to me : the values I read seem to slowly oscillate at the rate of 0.1 mV every 5 to 10 seconds. For the two transistors I am testing right now, the minimu...
by cyrdun
Tue Mar 27, 2018 9:06 am
Forum: Music Tech DIY
Topic: Mini-Modules : Minimoog DIY clone on its way.
Replies: 1923
Views: 269120

jdelgoulet wrote:
No need for strict matching. According to the Minimoog service manual you must be within 0.002 V (2mV).
So 0.588/0.600 is perfectly fine.
thanks :)
by cyrdun
Sat Mar 24, 2018 12:25 pm
Forum: Music Tech DIY
Topic: Mini-Modules : Minimoog DIY clone on its way.
Replies: 1923
Views: 269120

Hi,
how accurate should the transistor matching be?
I have a 3 3/4 precision multimeter, I get values between transistors like 0.600mV, 0.588mV, etc, do I need a strict matching? Or is some tolerance allowed?
Thanks in advance :)
by cyrdun
Fri Mar 23, 2018 11:49 am
Forum: Music Tech DIY
Topic: matching transistors - DIY
Replies: 481
Views: 78033

Gosh I am so stupid lol. I was measuring it the wrong way all along.
(I won't tell you how, even the stupidest way you could think about, it was stupider)
Now I have values like 0.6mV, 0.558mV, etc.
Seems more like it should be.
Thanks a lot Synthiq for the help, much appreciated :).
by cyrdun
Fri Mar 23, 2018 10:30 am
Forum: Music Tech DIY
Topic: matching transistors - DIY
Replies: 481
Views: 78033

I've checked mi circuit, it seems ok to me, but well i'm a noob, maybe there is a mistake i've overseen?

Image
Image
by cyrdun
Mon Mar 19, 2018 12:10 pm
Forum: Music Tech DIY
Topic: matching transistors - DIY
Replies: 481
Views: 78033

Your test leads can act as antennas and pick up 50/60 Hz noise large enough to noticeable on the lowest voltage range. I see it, too and it is much worse on a multimeter with >1Gohm input impedance. If it bothers you, disconnect the leads to see if the reading go to zero. I've disconnected the lead...
by cyrdun
Sat Mar 17, 2018 2:02 pm
Forum: Music Tech DIY
Topic: matching transistors - DIY
Replies: 481
Views: 78033

That sounds too good to be true. Measure the collector-emitter voltage of both transistors to make sure they are correctly biased at 0.6-0.7V. Also make sure the supply voltage to the circuit is there. Otherwise no current is flowing and you would always read 0mV. Thank you :). I think I have to do...
by cyrdun
Sat Mar 17, 2018 11:38 am
Forum: Music Tech DIY
Topic: matching transistors - DIY
Replies: 481
Views: 78033

If you use it to measure voltage difference between two transistor emitters as in Ian Fritz' circuit you use the 400mV range and have a 0.1mV resolution which is enough for you. If you measure the voltage between base and emitter on a single transistor (like a diode test) you need to use the 4V ran...
by cyrdun
Sat Mar 17, 2018 10:16 am
Forum: Music Tech DIY
Topic: matching transistors - DIY
Replies: 481
Views: 78033

Is my multimeter resolution enough?

Hi, I'd like to know if my multimeter resolution is enough for matching transistors? From the manual it seems to be 3 3/4, but I don't really get what it means, especially the fraction. My aim is to match transistors for the Guinguin Model D clone, discussed in other threads on this forum. Thanks in...
by cyrdun
Mon Mar 12, 2018 11:26 am
Forum: Music Tech DIY
Topic: Mini-Modules : Minimoog DIY clone on its way.
Replies: 1923
Views: 269120

thanks Kipling :)
by cyrdun
Mon Mar 12, 2018 10:58 am
Forum: Music Tech DIY
Topic: Mini-Modules : Minimoog DIY clone on its way.
Replies: 1923
Views: 269120

C49 capacitor value on Analog Board

Hi,
I've just noticed that the C49 capacitor on the Analog Board has a value of 500pF in the building guide, but the link to buy it leads to a 470pF capacitor. I've bought the 470pF one as linked in the list.
What should be the right value?
Thanks in advance! :)
by cyrdun
Fri Mar 02, 2018 1:17 pm
Forum: Music Tech DIY
Topic: matching transistors - DIY
Replies: 481
Views: 78033

Ian Fritz's method for matching transistors

Hi, I need to match some pairs of transistors, and Ian Fritz's method seems both accurate and easy to put in place. However, I have two questions concerning his setup : what should be the value of D1? I have read that it would work with 15V power, would it work too with 9V power, ie power supplies f...

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