Step 3 build. Is this correct?

[billr]

Hi
I'm new to the forum and electronics. 7 months in it sometimes seems like rocket science but I've managed to do OK so far. Building a MD struck me as a challenge and something I could use instead of flashing LED circuits all the time.
I bought the MPP board online before learning about this forum so apologies in advance for not doing things in the best way. Wasn't aware at the time I needed a scope to build it so that's something I am learning also.

Can you check the pics to see if I have correctly completed step 3 ?
The scope I have is a cheap DSO150 about the size of a cell phone. Not great but maybe enough for now.
Here is what I did.

Set the time base to 50us at 2v. This way I see the biggest pulse on the screen. faster than that it dissapear's. Slower and its too small to see enough detail.
Adjusted to span 8 divisions on the screen. Assumed 8x50 = 400us
Have to turn the dial to 0.5ms in order to see any numbers. Top left. Nothing will show at 50us for some reason.
Looks to be about 80% of a division at 0.5ms and checks out with the math.
Adjusted R14 to 8ms
That coincides with 125pps
The numbers do tend to bounce around a little but its the closest I can get.

Does this look right to you?

If not, can you explain like you would to an idiot what needs to be done to correct it. My brain, what little there is of it struggles with understanding scope readings at the moment.

Thanks in advance.

[waltr]

The first scope picture shows a high pulse of 400usec and 0 to 12V.
I tend to count screen divisions rather than go by numbers displayed.

To measure frequency the scope needs to 'see' at least two pulses. So not sure if the second display's freq is correct.
However, IF the scope triggered of the falling edge and that edge is on the left edge of the screen then the freq is about 290Hz.
I would want to see two pulse to be sure.

If the period is 8ms then set the time base to 1ms.

[surfdetector]

I have done videos for all of the steps in the build of the Mini Pulse Plus. You might find them to be of some assistance to you.
https://www.youtube.com/playlist?lis...x32pI5m-di2GTf

Cheers

[billr]

The first scope picture shows a high pulse of 400usec and 0 to 12V.

Thanks for the reply waltr.
So this 0 to 12v reading is incorrect even though it is showing 400us ?
Have taken on board the other two points you made.
Will take a look at it tomorrow and see if I can get 2 pulses on the screen.

[billr]

Surf
Thanks for the vid link. You make it look easy.

[waltr]

Thanks for the reply waltr.
So this 0 to 12v reading is incorrect even though it is showing 400us ?
Have taken on board the other two points you made.
Will take a look at it tomorrow and see if I can get 2 pulses on the screen.

Unknown if correct. I don't know where that measurement is taken from. Maybe TP2 on MPP Rev E schematic?
Just saying What I see on the scope measurements.

FYI:
Please state which schematic you are using and where the scope probe is connected. This way we can give a better answer.

U

[surfdetector]

Surf
Thanks for the vid link. You make it look easy.

I am glad that you found the videos to be helpful. When you are trying to learn something new I find that often seeing what someone is talking about is more helpful than simply reading an explanation and that is why I do videos like that in order to make a contribution as I have gained so much from the many learned folk here on Geotech.
Cheers

[billr]

Ok some progress, some uncertainty.
I have volts now. Adjusted settings on 5v instead of 2v as I did last time. The numbers bounce a little but are in the ball park on 1ms setting.
Shown is the connection setup.
As are two pulses across the screen.
Probe connected to TP2 ground part of the probe on TP5

Uncertainty = the frequency changes at 2 and 5ms settings leaving me thinking "which one is the correct speed selection starting point"
Makes it tempting to adjust the trim pots all over again depending on what speed its running

[waltr]

The cycle time measurement with 1ms time base is the most accurate.
The reason the 2ms and 5ms time base measurements are different is due to the resolution of the scope's timing on the pulse edges.

This pulsing look good so move on to next step.

[billr]

OMG !! No way.
Man I am SO pleased to read that. Cant thank you enough. Typing this with the biggest grin on my face. I have struggled with this issue for weeks until I came across Diydetector online when buying the Barracuda kit. He suggested I sign up here for if and when I need assistance. There was a time back there I was thinking this is like playing the lotto. Was just about to post a pic of the scope set to 10ms with the same readings as 1ms and you clarified the reason.
THANK YOU both for your help.

[waltr]

Been there using many scopes and trying to figure out why the measurements are not good.

I see in the pictures you are building a part then testing. This is very good and makes troubleshooting easier.

Do keep us updated on your progress.

[billr]

Thanks waltr
Appreciate it
Building in stages makes good sense to me and I'm wayyyy too inexperienced to challenge better judgment.
Will do.

[surfdetector]

I came across Diydetector online when buying the Barracuda kit. He suggested I sign up here for if and when I need assistance. There was a time back there I was thinking this is like playing the lotto. Was just about to post a pic of the scope set to 10ms with the same readings as 1ms and you clarified the reason.
THANK YOU both for your help.

I see that you have purchased the Barracuda kit as well. I am also doing step by step videos of the Barracuda build that you might find helpful.
Cheers
https://www.youtube.com/playlist?lis...Ggr2TG8w_UJbRe

[billr]

Surf
Couldn't bookmark your link quick enough sir
It's arriving soon. Though in retrospect I guess it would have been better for me as a beginner to have started the cuda build before the MPP to familiarize myself with the builds layout and structure after reading the online manual and comparing the two in complexity. There are certain assists with the Barracuda to help a newb. However until recently I didn't know anything about these machines. Seems the MPP is the next level. Frustration made me buy the barracuda after failing to get anywhere with the MPP for weeks.

I might have a question for you re your step 4 video.
Wont bug you tonight.
Thanks again

[Matt_Rowe]

surfdetector is great help and his videos are great, ive looked at them and have a kit coming from from silverdog since surfdetector makes it look so simple. surf always responds to my question with out any problems, ect, just like all the folks here in this forum, thats why i joined, these guys must all be EEs