Search found 543 matches

by russlk
Thu Nov 15, 2012 10:54 am
Forum: General Discussion
Topic: i need opto-isolator help please
Replies: 9
Views: 1677

Re: i need opto-isolator help please

What you need is a normally closed opto relay such as Omron G3VM353A; it is open when energized. Mouser #653-G3VM-353A.
by russlk
Sun Aug 28, 2011 7:15 pm
Forum: Robotics
Topic: need help and guidance on motor and control for a project
Replies: 2
Views: 2323

Re: need help and guidance on motor and control for a projec

What you want to do is exactly like a printer. You can use a DC motor with a segmented disc (counting wheel) and sensor to know how far the thing has moved, or you can use a stepping motor and count the number of steps. You will need to be able to program a microcontroller which will handle the coun...
by russlk
Tue Jul 21, 2009 6:24 pm
Forum: General Discussion
Topic: Class D amp in N&V Q&A
Replies: 41
Views: 3598

Re: Class D amp in N&V Q&A

My apoligies for taking so long to get to this thread. I understand the confusion, I don't understant it myself! I don't know what I was thinking, I have only one half of the needed circuit. This circuit can only drive the positive alternation of the audio, as was correctly noted. I think one soluti...
by russlk
Fri Jul 04, 2008 6:14 pm
Forum: General Discussion
Topic: That diode in solar panels...
Replies: 6
Views: 2057

I imagine that some low quality solar cells have significant reverse leakage. The ones I have tested have no measurable reverse leakage and I do not use a diode.
by russlk
Tue May 22, 2007 6:16 am
Forum: General Discussion
Topic: Magnavox 27TS52 C103 Television
Replies: 8
Views: 2691

Look inside, the vertical adjustment may be labeled. Otherwise you need to buy a service manual.
by russlk
Sun Feb 04, 2007 4:05 pm
Forum: General Discussion
Topic: dealing with small drill bits/holes
Replies: 15
Views: 5059

"the pads in Eagle are often so small that even if I don't ruin the pad between etching and drilling, there's not much room for the solder to stick. " The pads are sized for plated thru holes. For hand soldering, it would pay to go into the library and change the sizes. It is easy to do, just click ...
by russlk
Thu Dec 28, 2006 7:17 pm
Forum: General Discussion
Topic: Electrolytic capacitors in series...
Replies: 20
Views: 3896

So, what is the purpose of the capacitors?
by russlk
Mon Dec 04, 2006 2:17 pm
Forum: General Discussion
Topic: reversing motors??
Replies: 5
Views: 1581

I know that a single phase motor can be reversed if it is built that way. Reversable motors have two stator windings and you reverse one to make it turn the other way, I believe.
by russlk
Mon Dec 04, 2006 2:12 pm
Forum: General Discussion
Topic: TURBOFLARE 360 LED EMERGENCY LIGHT
Replies: 5
Views: 1845

From the picture it appears that there are 8 LEDs arranged around the circle, which are lighted one after another. All you need is a "LED chaser" circuit and some packageing. But, for $22.95, I don't think you can build one that cheap.
by russlk
Sun Nov 19, 2006 7:52 pm
Forum: General Discussion
Topic: PLC practice controller??
Replies: 7
Views: 2526

If you ask Allen-Bradley, they might give you one for free. I can't hurt to ask. Manufacturers often give out free samples.
by russlk
Sun Nov 19, 2006 7:22 pm
Forum: General Discussion
Topic: Underwater connector problem
Replies: 16
Views: 3674

When I worked in Ocean Systems, we had to make underwater connections that would survive 2000 feet of sea water. We used a sticky material similar to what is now called "bitchethane". The higher the pressure, the better it sealed.
by russlk
Mon Oct 02, 2006 6:25 pm
Forum: General Discussion
Topic: basic transformer question?
Replies: 6
Views: 2127

I believe that the most correct answer to "why have a center tap" is that full wave rectification with 2 diodes has AC flowing in the secondary so less iron can be used and still avoid saturation. Full wave bridge rectification works that way also but back in the day of selenium rectifiers, a center...
by russlk
Mon Oct 02, 2006 6:09 pm
Forum: General Discussion
Topic: October Issue
Replies: 17
Views: 4490

I don't have mine yet, but I have noticed that publication date varies quite a bit, month to month.
by russlk
Sat Jul 22, 2006 4:20 pm
Forum: General Discussion
Topic: Maximizing Radio Efficiency
Replies: 18
Views: 4199

High speed modems are able to send 56K over 3kHz phone lines, take a look at how they do it. Phase modulation, but I don't know the details.
by russlk
Wed Jun 28, 2006 8:04 pm
Forum: General Discussion
Topic: Sangamo transformer N17-T-72484-6834/881127 need datasheet
Replies: 4
Views: 2366

The 2 pin winding is probably an 8 ohm secondary. connect an audio oscillator to the secondary and measure the transformation ratio. The power rating can be estimated from the size and weight. What else do you need to know?