Joerg wrote in news: snipped-for-privacy@mid.individual.net:
Sure, but again, that's part of the appeal of making widgets that all use a single device or small number of parts. Means such adjustments don't have to be made that often. And again, this is as much as exercise in establishing safe operating areas, as much as anything else...
Joerg wrote in news: snipped-for-privacy@mid.individual.net:
Or any number of one-offs. That's actually the idea. Where labour is the biggest obstacle (lack of automation, and a desire to do as much of it here as possible), it pays to make a few widgets for a small demand, as one-offs, and test them individually too. And an LM317 is very convenient, a lot of function hiding behind three pins, and enough heft to do serious work of its own. It's a very attractive device and saves a LOT of board layout work.
Careful what you wish for! >:) I have a hair trigger as this thread shows..
I don't really see a connection there. Certainly there's plenty to be learned from applying ICs such as the LM317 in unorthodox ways, but there's also plenty to be learned from studying the "right" way to solve a specific problem. Indeed, often the "new" right way comes about from someone experimenting with the old ways and having a flash of insight.
I'm all for people experimenting and figuring out interesting new applications for circuits originally designed for different applications, but I'm also all for examining the works of the likes of Phil and Joerg and Jim since they have a demonstrated track record of building rock-solid designs.
In a hobbyist environment, one should certainly try out whatever wild ideas pop into their heads. In a work environment, while engineerins shouldn't generally be discouraged from trying out wild ideas :-), they need to be prioritized based on the perceived risk, time/resources needed to experiment, other project priorites, etc. I've seen firsthand someone's clever idea costing lots of money because the idea turned out to have unforeseen limitations -- any time you're proposing something wildly different from the traditional approaches, be sure to budget for plenty of testing time. On the other hand, you have John's company, where many of his products are completely unique based on his ability (and his employees') to successfully incorporate a few wild new ideas into viable products.
Yes. We did wind up with a reel of FR804's that snap nicely, maybe decent PIN diode material, but we went to a bigger part in the end, higher voltage and more power dissipation.
It was fun, but we only sold a few.
You should probably use real RF power PIN diodes, like Skyworks/Microsemi/Aeroflex. They have doping profiles that give absurdly long recovery times, so it takes very little DC to control a lot of RF. I used exotica because I needed a huge amount of power dissipation capability when we were running at 500 KHz.
"Joel Koltner" wrote in news:3Wlcm.493461$ snipped-for-privacy@en-nntp-02.dc.easynews.com:
That's exactly how I improve code when I write it, I look at what aorks best and always revisit to see if there;s a further improvement because there often is. But there is also context. In several posts here I've accounted for the context of my decision to try this LM317 wheeze. There's no reason not to try it, and a few good ones to try it.
"JosephKK" wrote in news: snipped-for-privacy@4ax.com:
Yes, I was sent an Intusoft newsletter that contained just such an animal, but it's based on a Hitachi 3mW IR diode, I think. But as a 'dead' diode with facet damage from ESD or other surge usually behaves very similarly to a live fresh one, electrically, AND most high power diodes have no monitor photodiodes anyway, there's nothing wrong with only two terminals. What is then critical, if it's to be driven hard, is to include temperature monitoring in the model. In practise diodes will vary but the setting will be a set-and-forget one based on a single measurement of power at maximum drive, once the thermal compensator works. I did this once (before I ever looked into spice) using an LM317 and some thermistors in the sense resistance network. It sounds crude, but I calculated it in some detail, and it worked well. Apart from that LM317, the entire driver was discrete passive parts. (Wasn't modulated though, have to add stuff then.)
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