Search found 218 matches

by k7elp60
Wed Sep 03, 2008 6:21 am
Forum: General Discussion
Topic: 9.6 volt dc @1-2amp adapter for 12volt auto application
Replies: 3
Views: 1265

You could use a LM338, and a heatsink to dissipate about 6W.
by k7elp60
Tue Aug 19, 2008 1:35 pm
Forum: General Discussion
Topic: 7 Segment Displays and Luminous Intensity
Replies: 3
Views: 1381

Hi there Ken, Oh that's interesting. That suggests that a white color will appear brighter to the human eye than a red color. In this case, you can use my comparative intensity measuring instrument (can be huild at home for almost no cost at all) to compare the white to the red and determine exactl...
by k7elp60
Fri Aug 15, 2008 5:45 am
Forum: General Discussion
Topic: 7 Segment Displays and Luminous Intensity
Replies: 3
Views: 1381

Hello MrAl, I have not purchased any of the blue segment displays. You have an interesting question. I am working on a project that I want to put red LED's in series with white LED's. As you know the forward current in the LED affects the luminous intensity. I connected one red and one white LED of ...
by k7elp60
Sat Aug 09, 2008 7:25 pm
Forum: General Discussion
Topic: Help on photoresistor - how to reverse?
Replies: 9
Views: 3296

I built a digital clock with a clock chip (NTE2061). My displays are 4 inch 7 segment that uses about 12V for the displays. The display has its own regulator. I used a photoresistor to sense ambient lighting, and when the room gets darker the voltage to the displays is decreased. I used an op amp wi...
by k7elp60
Tue Jul 08, 2008 2:46 pm
Forum: General Discussion
Topic: Easily assembled single in-line connector
Replies: 22
Views: 6569

You might want to consider the MTA series by TYCO(AMP) A digikey part # is A30994-ND. I have used a lot of similar ones that used to be made by Panduit. They were CT100f22-XX. I still have some and the manual insertion tool. The CT100F28-XX is for ribbon cable. 28 guage wire. The FXX is the wire siz...
by k7elp60
Tue Jun 10, 2008 6:11 am
Forum: General Discussion
Topic: LED'S as indicator lights on 110 volt a.c.
Replies: 11
Views: 3168

Here is a circuit that will work. The diode is necessary to prevent the reverse polarity damaging the LED
Image
by k7elp60
Sat May 03, 2008 1:44 am
Forum: General Discussion
Topic: Numbers
Replies: 22
Views: 5144

This bring brings up something I have always maintained about the AM radio detector. Most explain the AM radio detector as a simple rectifier. I think it is a mixer, that is mixing the carrier and one of the sidebands to get the difference. What confirms this to me is in SSB reception the carrier is...
by k7elp60
Thu Apr 24, 2008 7:05 am
Forum: General Discussion
Topic: Blue transfer paper
Replies: 21
Views: 5170

I think having the board really clean is the key. I do my boards with a different process. I use positive sensitized boards and create my artwork and print the pattern on a clear transparancy. I found an inkjet printer that works excellent(Epson R200). I expose the boards, develop,etch,drill and tin...
by k7elp60
Tue Apr 08, 2008 7:53 pm
Forum: General Discussion
Topic: Miniature Numeric Display - Is it possible?
Replies: 10
Views: 3288

Re: Miniature Numeric Display - Is it possible?

I'm trying to find a way to make a small numeric display device with at least three digits, ideally five, to display numbers in increments of 50 (or 5 with a smaller display). Display would be on top, with tiny buttons on the sides. Four buttons: +50, -50, +1000, -1000 with on/off. Size would have ...
by k7elp60
Fri Apr 04, 2008 6:16 pm
Forum: General Discussion
Topic: Front Panels
Replies: 23
Views: 6100

Ihave been using transparency film. Reversing the image printing with my epson R200 printer then glueing the transparency to the panel with 3M spray adhesive. Here is a picture of a 12/24 volt power supply.

Image
by k7elp60
Sat Mar 29, 2008 5:54 am
Forum: Up For Grabs
Topic: LA2730 Dolby B-type noise reduction system
Replies: 3
Views: 3415

They are gone, shipped them out on Thursday.
by k7elp60
Sat Mar 22, 2008 7:48 am
Forum: Up For Grabs
Topic: LA2730 Dolby B-type noise reduction system
Replies: 3
Views: 3415

I received a PM over month ago regarding these IC's. At the time of the personal message exchange I had lost track of the IC's. I thought I had discarded them, but I just found them. I have lost the personal messages so they are still available. All I remember was that the person that wanted them wa...
by k7elp60
Sun Mar 16, 2008 8:32 am
Forum: General Discussion
Topic: Happy Pi Day!!
Replies: 8
Views: 2940

Well, if its the same to you I would rather have my cake and eat it too!
by k7elp60
Thu Jan 31, 2008 8:21 pm
Forum: General Discussion
Topic: Primecell
Replies: 13
Views: 3494

I used to work in a independant electronic distributor that has a value added department. In that department they rebuild battery packs. One reason that tabs are spot welded to ni-cad and nickle-metal hydride cells is that the soldering temperatures can damage the rubber seals on near the + terminal...
by k7elp60
Tue Jan 15, 2008 7:53 pm
Forum: General Discussion
Topic: Ponder this for the new year...
Replies: 16
Views: 4424

I honestly believe rf transmission is about the most efficient transfer of energy I can think of. An area that has truly amazed me is skip zone foot print for short wave. Wether it be long skip or short skip. Let me explain. I am an active amateur radio operator(ham). I check in to a net on 40 meter...