the IC that i use is limited to 49% i am trying to obtain a 100% by pluging the pwm on the transformer!

 

Hi eric i use bread boards for testing maybe the error comes from that!

 

hi Matt,
Bread boards do have limitations with some circuits.
The inter pin row capacitance and insertion resistance can cause problems.
I guess you had adequate decoupling of the BB power rails.?

Have you had the chance to try the buffer mod.?

E

 

eric
Have you had the chance to try the buffer mod? sorry no
i guess you had adequate decoupling of the BB power rails.
here is my model!

 

hi,
I bought a batch of Arduino Nano Shields that came with BB's similar to your image, very disappointment with their performance.

What's your next planned step with the project.?

E

 

Eric
next step is trying to synchronize the pwm with the ic and connect it on the transformer
thats why i need a fixed frequency (hope we will find a solution)!

 

hi Matt,
Look over this option for a precise frequency triangular wave signal source.
E

 

hi Eric thank you i will test that and give a result!
regards!

 

Eric i have turned around the net for a circuit application but it seems complicated for me! can you give me a schematic to test it?
thank you!

 

hi,
Its also new to me, but I did find this data.
https://www.allaboutcircuits.com/pr...m-generator-analog-devices-ad9833-ATmega328p/

I will look it over later.

E

Added
https://www.element14.com/community/docs/DOC-68715/l/evaluation-board-for-ad9833

also

https://www.instructables.com/id/Signal-Generator-AD9833/

 

hi Matt,
Found this module
https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313&_nkw=ad9833+module&_sacat=0

E

 

Hi its a frequency generator from 0,1 MHZ to 12mhz not a pwm! nevermind thank you!

 

hi,
It was not for the actual PWM section, but the 'tri' generator, which appears to be the section thats got the frequency shift from 0% to 100%
E

 

Hi Eric you think that the triangular wave is maybe the origin of the problem of unstable frequency?

 

hi Matt,
Have you tried the test with that buffer added.?
E

 

Hello Eric yes ive tried with the buffer mode! the result is the same! i will try another solution!
thank you!
best regards

 

Hi Matt,
Can you confirm the supply voltage is it 5Vor 12V, also could you measure the actual voltage on the wiper of the Mod pot at the PWM limits.

E

 

hello Eric
12Vdc to the 339
12Vdc to the pot (47K)

 

hi matt,
Have been running tests using the resistor divider and the pot, nothing shows any change in frequency.
That is 4k7 > 47kpot > 4k7.

When the pot is at 0% rotation what is the Mod voltage, also what is the Mod voltage when the pot is at 100%.

E

Update:
LTSpice two examples of the circuit, pot 0% and pot 100%.
The frequencies are identical. at 227Hz.


Added:
Showing the Mod voltages at the lower and upper limits of the 'tri waveform.

 

Hello Eric thanks i will change to a TPS43000 for a synchro frequency at 100khz!