Replies to Minipulse Plus

[6666]

This little video shows the 555 TX pulse at top and the out put pulses from the 4017, initially you see the first sample and EF pulses
then by joining all outputs together you see the GB pulses added.
BTW this is the 4093 circuit.

https://www.youtube.com/watch?v=DKhV2KobDVA&feature=youtu.be

[Davor]

Nice to hear that

[6666]

Hi Davor, I have some good news, back later.

[6666]

After doing some bench testing the toggle point for a 4011 with a supply voltage of 4.67 volts is about 2.15 volts.

[6666]

My apologies to Sinclairuser, it was the schematic drawn by Silver dollar post #501.

[Davor]

Makes sense. I did not pay much attention to these values, I assumed 47pF -22k should be OK, but surely the CMOS input capacitance will limit the spikes and even disable resetting function if resistances are too high and a coupling capacitance too low.
I introduced 47p 22k values in a schematic "Cor 2" in post #416 and ... did not test it. My bad.

Nice catch

[6666]

I've been experimenting with the values from the Sinclairuser schematic in your gb sim
if you add the extra 10k which is R4 in the MPP in series with the 47pf and 22k and 22k the reset pulse from the 4011 just flat lines and stops working
if you up the value of the 47pf cap to about 100-150 pF in the sim, then the 4011 gate starts to trigger correctly, will try this tomorrow in real circuit.

[6666]

Hi Davor, somewhere between your GB sim and the schematic drawn by Sinclairuser some of the values on the reset line have changed from 220p 10k and 10k
to 47p 22k and 22k with these new values I only get .5 volt positive and just barely 1 volt negative is this voltage enough to trigger the 4011 gate ?

http://s15.postimg.org/k5y25w5y3/reset_pulse_4011.jpg

[Davor]

Yes, this seem a 4017 problem. It is not resetting properly. See what happens at pin11 of 4017. Also see if 4017 receives a reset pulse at pin15 or not.
The circuit works as follows... 4017 keeps pin11 high (from the previous cycle) which prevents the oscillator from oscillating. The falling edge of 555 output creates a short reset pulse that puts all 4017 outputs low, and hence enables the oscillator to start oscillation. The first oscillator pulse duration is adjustable relative to the oscillator period, hence GB adjustment. 4017 counts 9 pulses until the pin11 goes high again and stops oscillation. When 555 output goes low everything starts all over.

There is a way to optimise pulse rate in a way that no time is lost after EF pulse until Tx charge starts, and hence improve the SNR of a whole rig. I'll try that.

[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.

[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]

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.

[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]

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.

[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.