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Re: BJFE-Baby Blue
Posted: 01 Feb 2018, 08:37
by Jone the Bone
Nick123 wrote:I think I have found an error in the last schematic.
Only the wiper of RV2 should be grounded.
There is no error. In this circuit it doesn't matter, it's only an another way to connect a potentiometer.
Re: BJFE-Baby Blue
Posted: 18 Feb 2018, 14:48
by momo lab
Hi everyone, I'm back!Sorry for not coming so long, but our country has a “Great Wall firewall”，So I have to resort to some network tools to normal visit。
BBOD I have completed the test, 1N4XXX diode for the circuit sound will be bright and thin, so I had to modify the EQ part.Parallel into a 102 capacitor will sound almost exactly the same。
I wish you have fun, thank you.
Re: BJFE-Baby Blue
Posted: 01 Mar 2018, 11:32
by Manfred
Hi momo lab,
I would very much appreciate it if could you measure the drain and source voltages an give the read values to us.
Re: BJFE-Baby Blue
Posted: 04 Mar 2018, 10:52
by momo lab
Manfred wrote:Hi momo lab,
I would very much appreciate it if could you measure the drain and source voltages an give the read values to us.
Re: BJFE-Baby Blue
Posted: 04 Mar 2018, 15:01
by Manfred
momo lab wrote:Manfred wrote:Hi momo lab,
I would very much appreciate it if could you measure the drain and source voltages an give the read values to us.
QQ截图20180304185035.jpg
Thanks for the hint, I checked the topic twice, but I have overlooked.
Re: BJFE-Baby Blue
Posted: 06 Mar 2018, 10:05
by Manfred
After the measurement, the first stage FET voltage is 4.62V and 1.72V, the second stage FET voltage is 4.72 / 1.68 and the third stage is 5.55 / 1.44.
I got a bunch of 2N3822 FETs, which are almost equal as the 2N5952 FET, except the maximum voltage and current values.
I ran a curve traces of it, to drawing in the resitor values in found characteristic curves graphic.
The graphical soultion gave values in the vicinity of the read values of momo lab's measurement,
therefore the 2N5252 seem to be the right choice.
Re: BJFE-Baby Blue
Posted: 08 Mar 2018, 13:11
by ray86
Fairly straight forward JFET circuit with hard clipping in the 2nd stage
Re: BJFE-Baby Blue
Posted: 08 Aug 2018, 10:19
by Dingleberry
It looks to me that the diode is 2A / 1200V diode, most likely rectifier diode or schottky of some kind.
That's probably the obsolete part of that pedal because the production was stopped because of parts shortage (or at least that's what I have heard).
Re: BJFE-Baby Blue
Posted: 08 Aug 2018, 17:23
by Manfred
Dingleberry wrote:It looks to me that the diode is 2A / 1200V diode, most likely rectifier diode or schottky of some kind.
That's probably the obsolete part of that pedal because the production was stopped because of parts shortage (or at least that's what I have heard).
Have a look at the post further up, mom lab measured the original diodes
The threshold for this diode is 0.536v and 0.523v
I traced an obsolete rectifier diode found in an old tube amplifier as a part of a HV brigde amplifier.
The case has a rectangular shape and no imprint.
The traced values are surprisingly close to the measured values.
I therefore believe that it is rather a rectifier diode than a schottky type.
By comparison, the interpolated curve of a BY133 diode.
- BY133.jpg (49.33 KiB) Viewed 3306 times
Re: BJFE-Baby Blue
Posted: 09 Aug 2018, 15:53
by Manfred
Retrospectively, I have to say that the BY133 does not produce the desired value,
I am continuing to seek for the matching diode.
Re: BJFE-Baby Blue
Posted: 12 Aug 2018, 14:42
by Dingleberry
Found an inside-view picture of the new One Control Baby Blue from a japanese site.
Most likely those diodes in the One Control version are BY448V diodes. It's a 1500V 2A diode.
Kind of correlates to the 2A1200 of the original BJF unit. High voltage 2A rectifier diodes in both of them.
Re: BJFE-Baby Blue
Posted: 12 Aug 2018, 14:56
by Manfred
Most likely those diodes in the One Control version are BY448V diodes.
Thanks, it helps me, I will buy some and trace the curves.
Re: BJFE-Baby Blue
Posted: 20 Aug 2018, 17:09
by Manfred
Today, I received my ordered Diodes.
The BY448 Diodes were difficult to get and are very expensive,
that's why I bought a bunch of 40 BY458 diodes for a favourable price.
The diffrence between the both types is only the maxium reverse voltage.
The PN-junktion curve in the common data sheet is the same for both.
The measuring of all diodes results in a mean value for the threshold voltage of 0,608 Volts at 5 Milliamps,
with a deviation of 0.006 Volts.
The threshold voltage at ~0,9 Milliamps is.0,516 Volts, which is close to the measured original values of 0.536 and 0.523 Volts,
so the BY458 should be functioning well.
Re: BJFE-Baby Blue
Posted: 27 Oct 2020, 22:06
by Marcocu
Hi Momo, how are you? I have contact you from freestompboxes.org. Iam a
stompboxes fan and i tried to make a Baby Blue OD using this schematics
http://effectslayouts.blogspot.com/2017 ... d.html?m=1
and reading your post in freestompboxes. You have Made a great work by the
way! But i had problems and i couldnt make it function. I used 1N4001
diodes and 2N5952 transistors. I also used 470nF electrolytics capacitors
in stead of poliester. I can't find the mistake, could be the diodes or
transistors? Does the schematics from that website rigth? Iam trying luck
with this message, hope all the work done worth it and i hope you could
answer.
Greetings.