Search found 1182 matches

by Bob Scott
Sun Oct 27, 2013 1:02 pm
Forum: General Discussion
Topic: Info / schematic request
Replies: 15
Views: 14250

Re: Info / schematic request

*Moving this here in hope of a response. I am inclined to believe that the problem is either in the preamp section or in the selector switch on the back panel that chooses between stereo and 4-channel. With no input and a speaker connected to the outputs, each one has hiss in all modes. So, any hel...
by Bob Scott
Wed Aug 14, 2013 10:48 am
Forum: General Discussion
Topic: Looking for large plastic gears...
Replies: 10
Views: 2316

Re: Looking for large plastic gears...

Thanks, Tzap. No luck finding such animals; but is not something that I ought to have, so if some day they show up, I may go for them, if the interest of a kid still exists by then. John: A sort of clumsy kid admires my skills, my workbench, my boredom and my time availability and wants to try the ...
by Bob Scott
Thu Jul 04, 2013 8:17 pm
Forum: General Discussion
Topic: anyone in pittsburgh ? (i am visiting this weekend )
Replies: 1
Views: 1086

Re: anyone in pittsburgh ? (i am visiting this weekend )

is anyone in the area, would be cool to meet anyone in the area.. i am visiting here with friends this weekend... Whatever you do, please report back after your visit and tell us how it is there. Wasn't Pittsburgh famous for manufacturing steel! Then there was the rust belt.. I wonder how it all tu...
by Bob Scott
Tue Jul 02, 2013 3:25 pm
Forum: General Discussion
Topic: more power har har har!
Replies: 25
Views: 5396

Re: more power har har har!

dacflyer wrote:i used to put larger heatsinks on parts that were hotter then i was comfortable with..
in my book..if you cannot hold onto a heatsink for at least 10 seconds, then its too hot.
Yup! I call it my rule of thumb ( :mrgreen: ) for hot transistors and power ICs.
by Bob Scott
Mon Jun 17, 2013 8:52 pm
Forum: General Discussion
Topic: more power har har har!
Replies: 25
Views: 5396

Re: more power har har har!

Hmmm. E = (C * V^2) * .5, so the 350uF @400V cap can charge up to 28 Joules (watt-seconds) of energy. Discharge that in the typical photoflash time of one two-thousandth of a second and you get......a very short burst of 56 kiloWatts into the pesky insect. No wonder they explode! :grin: (well, maybe...
by Bob Scott
Tue Jun 04, 2013 2:59 pm
Forum: General Discussion
Topic: Constant AC current ?
Replies: 8
Views: 2276

Re: Constant AC current ?

I'd just buy a cheap string of white Xmas lights.

A series resistor would get warm because it would dissepate power. A series capacitor would conduct harmful high frequency spikes directly to the LEDs. I bet the Xmas lights use some combination of resistors and capacitor.
by Bob Scott
Thu May 02, 2013 7:13 am
Forum: General Discussion
Topic: Lost and Found
Replies: 0
Views: 1600

Lost and Found

Miguel....Externet,

I replied to an old message with a technical question from you in the "Lost and Found".
by Bob Scott
Wed May 01, 2013 3:35 pm
Forum: Lost and Found
Topic: Long time headache for a tone/radioteletype decoder display
Replies: 9
Views: 4789

Re: Long time headache for a tone/radioteletype decoder disp

Hi Miguel. This is a bit late, but it's the first time I've seen this thread. My bet is that the IC is a 4000B series CMOS logic hex inverter with sections of it used as linear inverting amplifiers. First clue is the power/ground terminal arrangement. I've used these in my design for R/C speed contr...
by Bob Scott
Fri Apr 26, 2013 8:56 pm
Forum: General Discussion
Topic: Turning on a transistor abruptly ?
Replies: 7
Views: 2056

Re: Turning on a transistor abruptly ?

Hi Externet, I don't know if you are aware, but with the circuit that you drew, adjusting the potentiometer to full 5V on the wiper will cause excessive current to flow through the diodes and transistor base. ie: whisps of smoke may arise and the transistor will "pop" audibly. (You probably knew thi...
by Bob Scott
Thu Mar 28, 2013 4:52 pm
Forum: General Discussion
Topic: Block Diagram Programs
Replies: 6
Views: 1727

Re: Block Diagram Programs

I'm a big fan of MS paint too (I previously called it paintbrush). Especially the XP and earlier versions. Althought the Win 7 version seems to have more capability, its ergonomics are off and I haven't gotten used to it yet. Its bitmap based and thus is limited in how you can resize or reposition ...
by Bob Scott
Wed Mar 27, 2013 7:42 am
Forum: General Discussion
Topic: Block Diagram Programs
Replies: 6
Views: 1727

Re: Block Diagram Programs

Whats your favorite program for making electronics block diagrams (I want text on the connecting lines) MS Office is close to minimal but its hell getting text near the connecting lines. I used to make diagrams with MS Word's build in drawing tools. Click on "View" menu to view the drawing toolbar....
by Bob Scott
Sat Mar 16, 2013 7:54 am
Forum: General Discussion
Topic: Pi Day
Replies: 7
Views: 1663

Re: Pi Day

CeaSaR wrote:Happy Pi day everyone! (3.14)

CeaSaR
Pi day is an early warning for "Look out! Find some green clothes! Just 3 days until St. Patrick's Day!"
by Bob Scott
Wed Feb 20, 2013 7:19 am
Forum: General Discussion
Topic: what is this thing ? Westinghouse LMT-100 Load controller
Replies: 4
Views: 2398

Re: what is this thing ? Westinghouse LMT-100 Load controll

i know it is some sort of a load controller, this unit looks like a electric meter, but it is inside the house, and connected to ( or it was ) a water heater. my question is. how did this work, and was it a self learning device ? or did the electric company control it ? i tried to find info on the ...
by Bob Scott
Mon Jan 21, 2013 9:00 am
Forum: General Discussion
Topic: USB port on television...
Replies: 9
Views: 2595

Re: USB port on television...

A 30 sec skip ahead would probably be adequate but cable company boxes sure don't... As I said, The cable co's DVR (Motorola DCX3400M) DOES enable me to skip through commercials of programs that I have given a few minutes "head start" by recording them, and playing them back while they are not fini...
by Bob Scott
Wed Jan 16, 2013 4:53 pm
Forum: General Discussion
Topic: USB port on television...
Replies: 9
Views: 2595

Re: USB port on television...

Thanks for the wealth of information Hackesup. It sure would be nice to have an external SATA drive to expand the DVR capacity but thats a no go,.... I recall that my DCX3400M does have an external SATA drive connector, and I was thinking of getting an external drive because my kids just gave me a 4...