Op amp clipper issues

Don't you understand the logic of making sales? If you design the unit to operate at the threshold, you save money! And later on, you can calculate the percentage of radio use and when the radio blows up, it's an incentive to buy a new car, that is, if the designer did the math correctly for the average radio listener. We wouldn't want it to fail before the warranty expired! Oh no, that would be counterproductive to the agenda at hand and very costly in the long run.

May not be such a good idea to do with safety items or make the car strand you to many times however, making your lovely sounding tunes fail and paint roll off is a small risk to take for another new car sale.

Jamie

Do you always have issues with being civil? Damned Google Groups & their constant influx of arrogant jerks.

PS: PLONK!!!

I love the LM317. I've abused the piss outta that beast. We sell stuff to students and I test for all sorts of loads. We've had one reported failure of an LM317 where someone hooked a power supply

George H.

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Hang a pile of cheap multimeters on the circuit and you'll quickly see where its going wrong. Dont use the original probes of course.

NT

And spammers. Don't forget them!

I wonder if there will be a special line to hell for those who sent

Thermal cycling is how you find the trip points on the bench. It requires characterizing a parasitic diode first so you know the die temperature.

I should have elaborated on blaming the engineer if the models are not accurate. It is the designer's problem for believing the models. ;-) Basically when things look dicey, you should always try to design in a process independent manner, hence my comment on adding parasitic diodes in the circuit to mirror leakage.

I use LM317Ls as current limiters, self-resetting fuses.

ftp://jjlarkin.lmi.net/LM317L_ilim.JPG

John

"John Larkin" wrote in message news: snipped-for-privacy@4ax.com...

Too bad about the saturation (dropout) voltage, but you can hardly get a more stable current limit in something like that. LDOs, besides being notorious for their designers having failed control theory class, generally have awful current limit ranges. You're probably stuck with that kind of variability or saturation unless you go with a current mirror sort of thing.

It won't work for transient voltage input protection, for which you still need a ~30V TVS or MOV, but what do you expect. Will work fine for protecting and isolating little bits of circuit from a bigger, protected supply rail.

Tim

It seems the issue was a bad op amp. After replacing it I am not having any more of those issues.

Nice photo. As an alternative to photos, have you tried writing the Rigol displayed image into a usb memory stick?

Ed

On Wed, 07 Dec 2011 15:11:50 -0800, John Larkin wrote: ...

Are you blanking out my part of the world?

Win7 ftp session on console:

C:\Users\Grant>ftp ftp> open jjlarkin.lmi.net Connected to jjlarkin.lmi.net. Connection closed by remote host. ftp>

Didn't ask for username? Ftp access from various browsers (chrome, opera, firefox, msie) simply fails quickly too.

I've been in hospital for last six months, only a lappy, no linux box to get better diagnostics. I've been unable to access your ftp site for months :(

And, not doing electronics design, I miss that. Hope to be out within days, or before xmas :)

Grant.

Works fine here with Firefox. Maybe Australia decided to killfile Larkin ?:-) ...Jim Thompson

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But then the postit note is harder.

George H.

How would I include the Post-It notes?

Besides, I like the way the photos look.

John

Some people can't open my FTP files... don't know why. Most browsers just work if you poke the link into the address bar.

I was posting them to Panoramio too, but google bought them and somehow trashed my account, with all its pics and Google Earth photos.

One day I'll get around to creating a real web site.

Get well!

John

I agree, the photo looks good. Easy to include text in your post to describe the contents of the post-it note: TO92 +12---[LM317L]---+---->

| | [1R] | Gnd

I'm not pushing that method, but I still wonder if you've done the acquire & save to usb stick thing. I haven't had much occasion to do that, but it seemed to work well when I tested it.

Ed

I've done that a few times in my life, but it's usually a hassle to set up. And I'd need to ID the photos and keep a separate log of which is which. A memory stick full of numbered photos doesn't carry any context.

We had a customer visit us on Thursday, with a bunch of fiber lasers to test. We ran about 15 or 20 setups. For each one, we stuck a post-it with context and a reference number on the scope and photographed that. Where the post-it wasn't big enough, we did just a number, and took a second shot of a whiteboard that explained the measurement, bearing the same index number. We really ripped through things. One of my guys is going to organize that in Word, into a nice report.

We're proposing to build a laser driver, values like half an amp or so, widths in the low hundreds of ps. Lasers are weird, with the light waveform being a non-obvious function of the electrical drive waveform. And they insist on using those awful DIP14 butterfly packages, pretty terrible for getting fast drive into the laser bars.

A while back I picked up a Tek 40 GHz o/e converter, and an SD30 40 GHz sampling head, just because they were up on ebay. Turned out to come in handy. I'm sort of a collector, and sampling heads are small, unlike being a collector for, say, old cars or tractors or carousel horses.

John