Search found 28 matches

by rolerbe
Wed Jul 14, 2010 7:38 am
Forum: General Discussion
Topic: Ed Roberts
Replies: 7
Views: 1323

Re: Ed Roberts

Dean, I'm sure the Computer Museum, now in silicon valley near Intel, would love to have an Altair 8800 for display. I don't recall seeing one last time I was there. They now focus on not just static displays, but in restoring the units to operation, so would be particularly interested if you have s...
by rolerbe
Mon Jul 12, 2010 10:22 am
Forum: General Discussion
Topic: audio preamp design questions
Replies: 10
Views: 1563

Re: audio preamp design questions

Problem solved. I breadboarded two versions, one with the LM 386, one with a gp op amp voltage gain stage and transistor current gain stage. Both worked fine. Will probably box up the 386 version as I can get it into a smaller box. My Gigaware set is similar to those Cesaer listed, but not identical...
by rolerbe
Thu Jul 08, 2010 11:48 am
Forum: General Discussion
Topic: audio preamp design questions
Replies: 10
Views: 1563

Re: audio preamp design questions

Dean, I checked r.e. your questions. The spec's for the Gigaware 2.1 Multimedia powered speakers indicate that the subwoofer is 4 Ohm, and the tweeters are 8 Ohm load. Why a 'powered' speaker system would present low impedance to the input is confusing, since there is an integral amp, but I guess th...
by rolerbe
Thu Jul 01, 2010 12:23 pm
Forum: General Discussion
Topic: audio preamp design questions
Replies: 10
Views: 1563

Re: audio preamp design questions

Good point. I actually have a gain control on the input side already. And, I put a Boostaroo inline which provides 12dB of gain and output volume still seems low (and no clipping). That's what drove the 20-30dB criteria -- basically another 12dB over the current rig (which I will take out).
by rolerbe
Wed Jun 30, 2010 8:44 am
Forum: General Discussion
Topic: audio preamp design questions
Replies: 10
Views: 1563

audio preamp design questions

I'm not getting enough volume in my patch together home theater system. So, I want to design a small in-line audio amp to give me some gain (maybe 20 - 30 dB) between the source output and (8 ohm) powered speaker input. The general design seems pretty simple, but, as I'm an amateur circuit designer ...
by rolerbe
Thu Aug 06, 2009 8:51 am
Forum: General Discussion
Topic: And now for something completely.. er.. Different?
Replies: 16
Views: 2626

Re: And now for something completely.. er.. Different?

Yea, but now that they are sponsoring a toor-day-france cycling team, customers will be flocking to the stores, 'cause bicycling and consumer electronics are just || that close! :smile:
by rolerbe
Fri Jul 24, 2009 8:26 am
Forum: General Discussion
Topic: Liquidating My Electronics Hobby
Replies: 25
Views: 3224

Re: Liquidating My Electronics Hobby

When I was in college (about a thousand years ago), there was an electronics surplus house called Eli's just off campus. They would take all the castoffs such as you are describing. It was a treasure trove for new upstarts like me and we built all kinds of "cool stuff" for cheap using the wonderful ...
by rolerbe
Thu Apr 02, 2009 1:09 pm
Forum: General Discussion
Topic: Perimeter Intrusion Detection
Replies: 17
Views: 2284

Re: Perimeter Intrusion Detection

If you could mount it high, looking down, say from top floor of house, etc. I.e. get out of the plane of the perimeter which has the obstructions, then how about night vision system to a standard security (time lapse) video recorder? Maybe a rotaing mirror system to get multiple area coverage, or a ...
by rolerbe
Thu Apr 02, 2009 1:02 pm
Forum: General Discussion
Topic: To PCB or not to PCB...
Replies: 21
Views: 2338

Re: To PCB or not to PCB...

I prefer to complete more projects with the help of others than to labour on every step. YMMV. Fair enough. Everyone has slightly different reasons for their hobby activities. In my case, I like to go as close to scratch built as I can, to make sure my 'book knowledge' is close to 'real' knowledge....
by rolerbe
Thu Apr 02, 2009 7:46 am
Forum: General Discussion
Topic: To PCB or not to PCB...
Replies: 21
Views: 2338

Re: To PCB or not to PCB...

Thanks Al. I'll try that with wire-wrap wire. As for Bigglez's value of time, etc., the big dividing line is if it is a for-profit or for-hobby enterprise. My goals for hobby projects are to keep me out of the couch-potato chair, and to produce working versions of my toys for less than 3X what I cou...
by rolerbe
Wed Apr 01, 2009 5:31 pm
Forum: General Discussion
Topic: Where are areas 1 and 2?
Replies: 7
Views: 1293

Re: Where are areas 1 and 2?

Areas 1 and 2 were moved to Area 51 :wink:
by rolerbe
Wed Apr 01, 2009 4:58 pm
Forum: General Discussion
Topic: To PCB or not to PCB...
Replies: 21
Views: 2338

Re: To PCB or not to PCB...

I have had good luck with the Pulsar http://www.pcbfx.com/ approach. One can make very professional looking boards very quickly and cheaply after the initial outlay (~$100). Their 'tankless' method (basically rubbing the FeCl onto the board with a sponge) works very well -- very quick and uses almos...
by rolerbe
Tue Dec 02, 2008 8:49 am
Forum: General Discussion
Topic: Radio Shack Leads the Pack! Warning: Unbelievable !
Replies: 9
Views: 1635

These results are simply incredible. :shock:

Not the RS I know (and "love"). They must really be slipping!
by rolerbe
Tue Dec 02, 2008 8:36 am
Forum: General Discussion
Topic: AC noise in audio ckt
Replies: 16
Views: 3265

V+ and V- also feed the op amp. I did just delete the whole PS from the ckt posted to try to 'simplify' the discussion. I won't be back to check do more hands-on troubleshooting for a couple of weeks, but will carefully check the PS then. Good point about the V- bypass cap for 4053, tho. That actual...
by rolerbe
Mon Dec 01, 2008 3:09 pm
Forum: General Discussion
Topic: AC noise in audio ckt
Replies: 16
Views: 3265

I guess what I should do (after eliminating the rogue AC input) is set fixed gains on the board for both stages that are high enough, then use the ouput pots to control output levels.

Thanks for all the input. I'm learning a lot and still having fun!