Replies to Minipulse Plus

[johnandles]

What prog opens sch. files
Eagle 7 errors on me?
Thanks
John

[6666]

SD Davor suggested R42 to be 6k8, your schematic has it at 68K.

[6666]

SD thats great work thanks,
could you please consider providing pads for a series diode between the coil and fet ?
if people dont wont to fit the diode then they just insert a jumper , but the holes need to
be about 1.2mm to account for the thick legs on some of the fast diodes, thanks.

[Silver Dollar]

Ok I fixed it. Here's a picture and the ExpressSCH file;

[Qiaozhi]

So I'm working on a MiniPulse build and hope to incorporate the gorund balance circuit
from the start. Here's my schematic. Can someone give it a look and make sure I have
everything correct? The power configuration is a bit funny...

[ATTACH]31140[/ATTACH]

The 100pF sync cap is missing between Q2 collector and U2 pin 7.

[Davor]

So I'm working on a MiniPulse build and hope to incorporate the gorund balance circuit
from the start. Here's my schematic. Can someone give it a look and make sure I have
everything correct? The power configuration is a bit funny...

It seem mostly OK. R42 needs some resistance in series, say 6k8, to prevent overload. Also there is no decoupling on U5 nor on U6.

[Silver Dollar]

Your welcome! I'm hopeing to make an upgrade board that will sit where the
removed components are and show the layout here. They would go in the yellow
box in this picuture;


Still trying to figure out how to connect the new board. Wires can break if handled a lot
so maybe stacked sockets so it can just plug in...

[WM6]

Many thanks, Silver Dollar, for GB upgraded schematic of MiniPulse.

[Silver Dollar]

So I'm working on a MiniPulse build and hope to incorporate the gorund balance circuit
from the start. Here's my schematic. Can someone give it a look and make sure I have
everything correct? The power configuration is a bit funny...

[josewashere]

Oh no... My cover has been blown lol

[Qiaozhi]

Found this on Youtube..
https://www.youtube.com/watch?v=FhXVteLVL0k

I pretty sure that video is from josewashere.
There's also a follow-up -> https://www.youtube.com/watch?v=D-QSH5nfJNE

[johnandles]

Found this on Youtube..

https://www.youtube.com/watch?v=FhXVteLVL0k

[Davor]

Murphy's Law came into play, and it got toasted, literally.

Perhaps a reverse polarity protection MOSFET is not a bad idea at all.

[adenyer]

I completed my minipulse plus a few days ago, although i have an old oscilloscope i couldnt get it to show the correct waveforms ( very old oscilloscope, new one on its way).
I followed the instructions and then read the post about Q2 and the resistors, but it all worked although needs tweeking, i did the capacitor mod in this thread straight away.
It worked straight away with my coil from my baracuda build. I also tried it with a rx coil of 360mh and a tx coil of 300mh and it worked perfectly.
If anybody is thinking of building one i would say go for it as it was a relatively easy build with nice instructions and the boards from Andy are just fantastic.

[Qiaozhi]

Thanks for pointing me to the proper link.
It is not clear to me which revision post #149 refers to.

Only this part of post #149 is relevant to your current problem:
========================================
Firstly, the battery pack I was using to test the MPP was getting low, so I grabbed a fully charged 12V lead-acid battery (7Ah) and connected it via jumper leads. Big mistake! Accidentally got the battery leads reversed and [literally] let the magic smoke out of the -5V regulator (U1). (Doh!) The only other component to R.I.P. was the TX 555 oscillator (U4). At least you now know which components are going to kick the bucket if you reverse the battery leads.
========================================

I am building the Rev C Minipulse; do R5, R9, and Q2 need to be installed?
Although there were no specific steps to add R5 and R9, the board looked "wrong" without them.
The components were included with the Rev C kit that I bought earlier this month, sp I put them in.

Yes, they need to be included.

Also, I have put together a testing sign-off sheet for this project. On step 3, I have been getting a 47 microsecond pulse width at TP1 instead of 58 microsecond.
U2 pin 2 seems to be OK, but not exactly sure what it is supposed to be.
When I get to step 6: TP1 channel 1 trigger, TP5 channel 2, short pins 1/2 or 2/3 on PL3, I don't think I really see what I am supposed to see.
I am using a second-hand Tektronix 2232 100 MHz oscilloscope, and have managed to see most of the waveforms acceptably. However, I never see anything looking like figure 10 in the rev C instruction document.
Thanks for the technical help and for keeping me motivated!

The reason for shorting the pins on PL3 is simply so that you don't have to fit the Reject pot to make tests at this stage of the construction. The result is the same as turning the Reject pot to its minimum setting. Without the short (or the pot fitted) the timing pulses will be missing.