Variable duty cycle and frequency with a 555

control the frequency and duty cycle(1% to 99%).

needed but when completing the circuit, I found that when varying the frequency.. the duty cycle was also changing !! or vice versa.

fast enough. I can see on the scope that the 555 pulse starts to deteriorates

Larkin has never had any... let alone any to give away >:-} ...Jim Thompson

control the frequency and duty cycle(1% to 99%).

needed but when completing the circuit, I found that when varying the frequency.. the duty cycle was also changing !! or vice versa.

not fast enough. I can see on the scope that the 555 pulse starts to deteriorates 2.5us while the lm393 starts about at 100us

control the frequency and duty cycle(1% to 99%).

needed but when completing the circuit, I found that when varying the frequency.. the duty cycle was also changing !! or vice versa.

not fast enough. I can see on the scope that the 555 pulse starts to deteriorates 2.5us while the lm393 starts about at 100us

Larkin's narcissism is without bounds. ...Jim Thompson

control the frequency and duty cycle(1% to 99%).

needed but when completing the circuit, I found that when varying the frequency.. the duty cycle was also changing !! or vice versa.

not fast enough. I can see on the scope that the 555 pulse starts to deteriorates 2.5us while the lm393 starts about at 100us

That they would be embarassing.

Read my posts.

I've posted Spice files, entire PDF sheets of schematics from real products, photos and layouts of real boards, some sketches with values, and some sketches without.

Why does a no-values topology bother you so much? Can't visualize how a circuit might work? Can't figure out values for yourself?

Every no-values thing that I've posted would work, except for a few that were fun and silly, and declared to be such. Pick one of my recent 5v/12v LED circuits and demonstrate why it won't work. I *can* demonstrate that one of Jim's doesn't work; in fact, he did it for me already. You didn't even try.

When we brainstorm around here, we might scribble dozens of circuits in one session, until we get one or two that we like. We certainly don't want to stop and do the math on every one while we're playing. Some things, like filters and some amplifiers, might take hours to finish up.

Is your PWM thing a crown jewel? Several PWMs come free in a typical PIC or an ARM. One of the TI chips has a PWM that interpolates between clock edges, to picosecond resolution.

Sounds like the type of person I would like to encounter on Usenet.

I would like it to be that way. Some people here want to make it combative or insert their Pecksniffian attitudes. ...Jim Thompson

So be that person. You appear to have managed it once in your life.

Yep :-( ...Jim Thompson

On 2013-04-25, captoro wrote:

control the frequency and duty cycle(1% to 99%).

here's how to do it with 2 555s. You'll need to use a fixed-pitch font to make this legible +V | .---------------------------. | | | | .--------+--------------------+--------+------------+ | | | | | | | | | . . . .|. . . . freq. | | . . . .|. . . . | | | . VCC(8) . __ | | . VCC(8) . | | | . . /| | | . . | out | `--RES(4) OUT(3)---/\/\/--+ +--RES(4) OUT(3)---------- | . 555 . / | | . 555 . | +----TH(6) DIS(7)-- | +--TH(6) DIS(7)-- \ | . . | . . \ / duty `----TR(2) CV(5)-- +------TR(2) CV(5)----->\ cycle . . | . . / / . GND(1) . === . GND(1) . | 10K . . . .|. . . . | . . . .|. . . . | | | | | ----------+----------------+------------+------------+-- neither control will be particularly liner (freq will adjust the period in an approximately linear fashion) and duty cycle will be non-linear in two different ways (and have dead zones at each end) one of the non-linearities can be improved by adding an NPN emitter follower between the potentiometer and pin 5. (collector to +v)

if you can use a variable capacitor for frequency you can use the single 555, two-diodes varialble duty cycle circuit that's all over the web.

LM339 ? there may be a way to speed that up,.

I AM that person, I've never deviated from that person.

However, I've ALWAY been intolerant of stupidity, aka narcissistic ignorance... a large quantity of which always seems to be in circulation on this group.

I've always tried to educate here, exhibited by over 400 schematics on the SED/Schematics page of my website. (Someone will count them on the page. A very large number are not indexed. I'll do that RSN :-)

However, I don't give away answers, I try to induce thinking for yourself by, heaven-forbid, saying "just run the math" (*)... which always gets me a snarky response, and statements that I'm wrong and they're right... and, when pressed, they say, "fact", followed by epithets :-(

So it's up to Larkin and his sycophants and his Pecksniffian echo to knock it off and start acting like adults >:-}

(*) Are there any real engineers here? If so, why don't you stand beside me and say something against the prevalent nonsense? Or is it that you are a secret voyeur, enjoying the performance of Larkin and his thugs? ...Jim Thompson

Jim, I've learned one thing in life, and that's that you can't change other people - only yourself. Especially in an online, text media such as Usenet, attempts to "correct" other people's personalities only result in you becoming that person. So, I repeat, be the person that your admirer thought that you were. Nobody here gets a prize for being right and people have the ability to make up their own minds based on the arguments presented. And lest you think that I'm singling you out, I have exactly the same advice for John, John and Phil (and a few others who I can't name because I killfiled them long ago for providing nothing but bluster or obviously misleading advice). Saying "I'll stop when they do" is a non-committment. Again, you are the only person whose behaviour you can change. And finally, yes I am an engineer and in my own unique way, I am standing beside you and calling out against this nonsense. Remember that my three options are(a) jump into this Internet pig mud wrestling match, which would simply debase my reputation, regardless of which side I took, (b) killfile the whole lot of you, which I have come perilously close to, but not done because you all occasionally (when you're not spewing vitriol at each other) post interesting, educational stuff or (c) try and convince each of you that these flamewars are a fool's errand. Well, that's my contribution to society for today. Maybe I'll make some pancakes...

JT has threatened to shoot me in the knees. That would change me some. Actually, if he ever did it, it would change him some too.

Actually,

Vermin eradication, or even maiming, doesn't change a man much.

Actually,

You're not decadent, you're just dumb.

--

John Larkin Highland Technology Inc

Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators

Actually,

Bwuahahahahaha! You keep believing that, dingledorf.

I was just venting. I'll stick to technology. You're right... I've never seen white trash converted to gentleman either >:-}

My last slam. Now I'm going to go join a convent ;-)

Sounds like a great idea. After the grandson's ice hockey practice... gotta go NOW. ...Jim Thompson

example...

Actually,

So how have your ongoing efforts to reform Jim been working out? Be the person you want to see on Usenet and ignore the others.

Ralph Barone Inscribed thus:

Actually,