Replies to Minipulse Plus

[Qiaozhi]

Some good news ... the Gerber files are now with Silverdog, so hopefully we'll have some PCBs available in a few weeks.

Please note that I've made some minor changes to the PCB at Silverdog's request:
1) Changed the PCB footprint for the cermet trimmers to 4-pin, to allow the use of both staggered and in-line types.
2) Improved the appearance of the bottom layer by eliminating an isolated island in the ground plane.
3) Tweaked a few traces (while making these changes) to improve track spreading.

Of course, this means I've had to update the project files. Also added a parts list and BOM with the missing external potentiometers that are not shown on the schematic.

[sinclairuser]

thanks george, i'm going to enjoy this one.

[WM6]

Exemplary made project, Thank you.

[Qiaozhi]

Finally, at last, and with no further delay, ... please find the complete details for the Minipulse Plus (updated / modified version of the original Pulse Technology Minipulse design) in the sticky post at the top of this section ->
Minipulse Plus

[Qiaozhi]

I tried to post this earlier, but due some forum problem I was unable to login. Suspected someone hacked my profile, ( message says i'm on my 6^th login attempt, I was not log once, no reset after timeout ?), even sent mail to Carl, to prevent someone to post stupidities here in my name (i'm doing well on my own), now everything seems to work, hope this is OK. Probably forum reliability issue.

It sounds like someone was trying to log into your account, but failed to do so. Hence the message.

[Qiaozhi]

!Problem! On both schematic and PCB problem exists with +5V distribution, pin 7 U2 is connected to 0V (bat+) via R11, on original PCB goes to +5V so U 2,3,4,8 are powered from +\-5V.


Also, too small raster for C10, better change to 200mil. I also suggest replacing C7, from 22u electrolytic to 470n film cap. Original value is unnecessarily high, not needed even for original PPS, just can produce trouble (increased LF\powerline leakage into integrator), and better not to be electrolytic type.

Tepco - brilliant! ... thanks for checking.

Oops! That was a silly mistake on the preamp power supply. Obviously that should go to +5V.
I will increase the pin spacing on C10 to 200 thou as you suggest (100 thou might be a little too small) .
In the original circuit, C7 is a 22uF tantalum, but these tend to be expensive are getting difficult to find nowadays. Anyway, I agree, the value is too large and I don't like using electrolytics in filter circuits. It might even be worth reducing it to 220nF to set the cutoff frequency at 72Hz, which is above the 50Hz and 60Hz mains frequencies (depending where you live). I'll set it to 470nF for now, and let others experiment.

Updated schematic and PCB coming later.

[Tepco]

!Problem! On both schematic and PCB problem exists with +5V distribution, pin 7 U2 is connected to 0V (bat+) via R11, on original PCB goes to +5V so U 2,3,4,8 are powered from +\-5V.


Also, too small raster for C10, better change to 200mil. I also suggest replacing C7, from 22u electrolytic to 470n film cap. Original value is unnecessarily high, not needed even for original PPS, just can produce trouble (increased LF\powerline leakage into integrator), and better not to be electrolytic type.


I tried to post this earlier, but due some forum problem I was unable to login. Suspected someone hacked my profile, ( message says i'm on my 6^th login attempt, I was not log once, no reset after timeout ?), even sent mail to Carl, to prevent someone to post stupidities here in my name (i'm doing well on my own), now everything seems to work, hope this is OK. Probably forum reliability issue.

[Davor]

It looks good. I'll check it tomorrow.

[Qiaozhi]

The Minipulse Plus details are posted in a sticky thread above.
Details of external controls, connectors, and description of operation coming soon .....

In the meantime, this is your chance to find any errors before I send the Gerber files to Silverdog for processing.