Replies to Minipulse Plus

[sinclairuser]

got some time to finish up the mpp and something i have noticed today was my kit is missing the 1 uf cap for c18, i had a wima 1uf so its ok.
but i have an extra .47u cap, my kit was bought ages ago so it may not matter but you never know.

[sinclairuser]

if one wanted to add c19 in to a b rev board, which end does the + go to, sending myself round in circles with this.
i know where it goes but does the + go to pin1 or pin4-8, it makes me mad when simple stupid stuff like this stalls me, since its all stuff i'm supposed to know.
thanks

[CAS]

C19 +ve goes to pin 4/8, -ve goes to pin 1

[Qiaozhi]

if one wanted to add c19 in to a b rev board, which end does the + go to, sending myself round in circles with this.
i know where it goes but does the + go to pin1 or pin4-8, it makes me mad when simple stupid stuff like this stalls me, since its all stuff i'm supposed to know.
thanks

CAS is correct.
To confirm this for yourself, have a look at the schematic for REV-D -> Minipulse Plus REV-D

[sinclairuser]

thanks, i have done it, it was a combination of senility and tiredness lol.

[6666]

Davor

I would like to have another try at your ground balance circuit, I was looking at making the first version that uses the 4093 chip
are there any real problems with that version compared to the new version with the 4011 ?

[Davor]

4093 is a Schmitt triggered device so the idea was to use that property, but after consulting multiple datasheets I realised that hysteresis of 4093 is slightly unpredictable. I therefore abandoned them.
I'd suggest going for the latest circuit instead, not just because hysteresis is more predictable there, but also because the GB tune is done as a ratio to the main sample, which makes GB setting work for different main sample durations without readjustment.
I decided to improve the original circuit by adding another counter and go with 1:3 or 1:4 main sample to GB, and also to integrate the Tx charge period within. that way I'd reduce attenuation with GB, and also I'd have the least possible idle time, therefore more depth. I'm lazy though, so don't hold your breath.

[6666]

Hi Davor thanks
I'm interested in this GB system again for a number of reasons, one is to see what pulse width comes out of the 4017.
if you are planning to add another counter is this attachment any help ?
cheers.

[Davor]

In a way that is the basic idea of adding another counter. You can't use D0 on a second counter because it is the same as D9 on a first one (or D8 in your attachment). Once I sort out some hiccups at work I'll see to the GB circuit.
There are other ways to realise this circuit, but I prefer 4017 as it enables combining various timings in wired OR style.

[6666]

Hi Davor
For my own interest, I made the first part of your GB circuit, just to see if I could get the reset pulse to work.

I made the complete 555 circuit on breadboard and getting a nice 58uS pulse and fed that pulse via a 10K into the pulse shaping net work c2, r3,r6, D1,
and I'm using pins 1,2,3 on both a 4093 and 4011, I can get a nice looking 2 volt pulse on pins 1and 2 but nothing out on pin 3
on either the 4093 or 4011.
I have 12 volts on the 555 and 5 volts on the 4093/4011 just like the MPP, but I'm puzzled why no
output pulse on either 4093 or 4011, as its such a simple circuit.
Here are what the pulses look like, with positive battery as ground as per MPP.
I did test the 4093, and can make an easy astable with pins 1,2,3.

[6666]

After sleeping on this, I've tried some ideas , its difficult to see the pulse on 4093 nand gate pin 3 on a cro for some silly reason
but after proving the gate works manually with logic probe, I used a frequency counter
and can read the 555 frequency at pin 3 of the nand gate, so I guess thats a step forward.

[sinclairuser]

thanks 6666, thats good to know, i'm watching developments on this, the are a couple of mods i'm interested in, the GB, the motion/non motion mod and swapping the mc14538bcp, with mc74hc4538a(ceramic) i have those in stock its basically the same chip but has a wider range and goes down to 1us.
but ground balance may be needed(hence watching this thread), only other thing i did differently was swap the tl071 and tl072 for tle2071 and tle2072.
i'm struggling with the enclosure at the moment, i'm at the caravan now till monday, but i will be getting stuck in when i get home.
its hard to make time for projects sometimes, every now and then you just have to say sod it and make the time.

[6666]

its hard to make time for projects sometimes, every now and then you just have to say sod it and make the time.

Yep sometimes you just have to do it.

[Davor]

Hi Davor
For my own interest, I made the first part of your GB circuit, just to see if I could get the reset pulse to work.

I made the complete 555 circuit on breadboard and getting a nice 58uS pulse and fed that pulse via a 10K into the pulse shaping net work c2, r3,r6, D1,
and I'm using pins 1,2,3 on both a 4093 and 4011, I can get a nice looking 2 volt pulse on pins 1and 2 but nothing out on pin 3
on either the 4093 or 4011.
I have 12 volts on the 555 and 5 volts on the 4093/4011 just like the MPP, but I'm puzzled why no
output pulse on either 4093 or 4011, as its such a simple circuit.
Here are what the pulses look like, with positive battery as ground as per MPP.
I did test the 4093, and can make an easy astable with pins 1,2,3.

I tested the circuit in a configuration at a post #403 at this very topic, and everything worked as it should. My 12YO son did the 555 part. Silver Dollar made amendment to a MPP schematic at #501. The 4011 obviously works.
I'll see to including the other 4017 soon.

[6666]

I'm starting to think that this circuit does not like my bread board and probably needs to be hard wired with solid solder joints on vero board .
The oscillator works, its hard wired to run continuously and triggered on the cro from the pin 3 555 tx pulse , there is some issue with the 4017
and needs more work.