battery chargers, again
in [Design]
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From: Joerg on 2 Oct 2009 13:56 John Larkin wrote: > On Fri, 02 Oct 2009 09:49:50 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > >> John Larkin wrote: >>> On Fri, 02 Oct 2009 08:59:14 -0700, Joerg <invalid(a)invalid.invalid> >>> wrote: >>> >>>> John Larkin wrote: >> [...] >> >>>>> Maybe I'll include an FM deviation trimpot on the board. ... >>>> Trimpot? Euww ... >>> The point being that, when the actual instrument is up and being >>> driven by chemists, I'd like a quick and easy way to play with the >>> spread-spectrum parameters to see the effects. I can always nail down >>> the values once I know what works best. I often use fixed resistors >>> but also put down pads for a pot so we can tweak the first articles >>> without soldering. >>> >> I just had my potmeter comeuppance yesterday. I am very much against >> those things and it proved the point. Built a tester jig for a client, >> just for engineering, they didn't want SCADA controls on that (tried to >> convince them and now wish they had agreed ...). Sure enough the Murata >> "10-turn" potmeter exhibits a huge dead spot around the point where they >> said they wanted it. Like a half turn of slack and you can't get the pot >> inside that area. Hurumph! >> >> I believe nowadays they just put cheap regular pots in there and roach a >> worm gear onto them so they can be called 10-turn. > > Yes. Single-turn trimpots are as good as, or better than, most > multi-turns. And the singles are less likely to jump in value if > shocked later. > > We did find a trimpot that makes a good DC-to-1 GHz gain trimmer, > which is really hard to do any other way. Digital pots have rotten > bandwidths. Ditto MDACs. VGAs aren't accurate at DC. Fets and such, if > you can make them fast enough, have distortion and temperature > problems. PINs don't work at low frequencies. Wot's a boy to do? > I mostly use FETs. Although that has gotten to be more of a pain since the SD5400 went on boutique pricing. You take one for the action and the 2nd on the same die to servo out the temp stuff at DC. More esoteric is the use of mixers (the DBM kind) as attenuators. Provokes expressions of disgust in design review. Well, not when you are da boss I guess. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Charlie E. on 2 Oct 2009 16:55 On Fri, 02 Oct 2009 08:13:19 -0700, Joerg <invalid(a)invalid.invalid> wrote: >Jim Thompson wrote: >> On Fri, 02 Oct 2009 07:59:11 -0700, Joerg <invalid(a)invalid.invalid> >> wrote: >> >> [snip] >>> Just got assembled boards back from AA-PCB yesterday. They threw in a >>> bag of trail mix. Sweet. Needless to say, it was all gone before I had >>> the first scope shots on the server and I wasn't too hungry at dinner time. >> >> Funny what extraneous stuff can end up in a shipment. Recently found >> a chocolate chip 2-pack in my Amazon order ;-) >> > >They seem to do that with all shipments. The one last week also had >trail mix in it but arrived at a client so their engineers got to enjoy it. Advanced Circuits always includes a bag of microwave popcorn... charlie
From: Joerg on 2 Oct 2009 17:05 Charlie E. wrote: > On Fri, 02 Oct 2009 08:13:19 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > >> Jim Thompson wrote: >>> On Fri, 02 Oct 2009 07:59:11 -0700, Joerg <invalid(a)invalid.invalid> >>> wrote: >>> >>> [snip] >>>> Just got assembled boards back from AA-PCB yesterday. They threw in a >>>> bag of trail mix. Sweet. Needless to say, it was all gone before I had >>>> the first scope shots on the server and I wasn't too hungry at dinner time. >>> Funny what extraneous stuff can end up in a shipment. Recently found >>> a chocolate chip 2-pack in my Amazon order ;-) >>> >> They seem to do that with all shipments. The one last week also had >> trail mix in it but arrived at a client so their engineers got to enjoy it. > > Advanced Circuits always includes a bag of microwave popcorn... > Darn, I never got that from them :-) But they were always good to us and on time, that's what really matters. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: krw on 2 Oct 2009 19:48 On Fri, 02 Oct 2009 08:08:08 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: >On Fri, 02 Oct 2009 07:59:11 -0700, Joerg <invalid(a)invalid.invalid> >wrote: > >[snip] >>> >> >>Just got assembled boards back from AA-PCB yesterday. They threw in a >>bag of trail mix. Sweet. Needless to say, it was all gone before I had >>the first scope shots on the server and I wasn't too hungry at dinner time. > >Funny what extraneous stuff can end up in a shipment. Recently found >a chocolate chip 2-pack in my Amazon order ;-) You guys must be buying crummy product.
From: Joerg on 2 Oct 2009 19:54
krw wrote: > On Fri, 02 Oct 2009 08:08:08 -0700, Jim Thompson > <To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: > >> On Fri, 02 Oct 2009 07:59:11 -0700, Joerg <invalid(a)invalid.invalid> >> wrote: >> >> [snip] >>> Just got assembled boards back from AA-PCB yesterday. They threw in a >>> bag of trail mix. Sweet. Needless to say, it was all gone before I had >>> the first scope shots on the server and I wasn't too hungry at dinner time. >> Funny what extraneous stuff can end up in a shipment. Recently found >> a chocolate chip 2-pack in my Amazon order ;-) > > You guys must be buying crummy product. Nah, they did a great job. And the trail mix was really good. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM. |