Search found 134 matches

by Chris Foley
Thu Oct 02, 2003 7:43 pm
Forum: General Discussion
Topic: Specs Needed for this Power Supply
Replies: 1
Views: 892

Re: Specs Needed for this Power Supply

You have a power supply with 120VAC nominal input, and 24VDC output at 6.5 amps. The power supply is "remote sensing", which means it can compensate for voltage drops across lengths of wire that will reduce the load regulation.<p>First, AC(L) refers to what electricians call L1, or the "hot" end of ...
by Chris Foley
Thu Oct 02, 2003 1:28 pm
Forum: General Discussion
Topic: RS232
Replies: 3
Views: 1034

Re: RS232

RS-232 Tutorial <p>Usually, you either use a straight-thru or null modem-type cable. Both are commercially available, but the pinout is in the tutorial if you want to roll your own. You have a large safety margin on RS-232, and you shouldn't worry about incorrectly hooking anything that's RS-232 up...
by Chris Foley
Thu Oct 02, 2003 7:33 am
Forum: General Discussion
Topic: device 74HC595
Replies: 5
Views: 1481

Re: device 74HC595

Hello again, Jukin. You've apparently got a noise problem. Not unusual in the real world. The thing is, sometimes problems like this are almost impossible to deductively troubleshoot without some major test equipment. Here's a few suggestions you can run through on inductive logic troubleshooting wi...
by Chris Foley
Sat Sep 27, 2003 8:27 pm
Forum: General Discussion
Topic: Old test meter need repair and callibration?
Replies: 8
Views: 1880

Re: Old test meter need repair and callibration?

Thanks for the sites, Edd! It's good to know they're there.<p>As we were talking about before, the first thing you want to do is look at the meter movement. The schematic says the movement is 50uA, approx 1800 ohms. Your first step is to use the screwdriver adjustment to get the meter needle to rest...
by Chris Foley
Fri Sep 26, 2003 8:18 pm
Forum: General Discussion
Topic: Old test meter need repair and callibration?
Replies: 8
Views: 1880

Re: Old test meter need repair and callibration?

Hi, Mark. Specific information invites specific answers (or even possibly scanned copies of schematics). Is it a 260, 270, or what?<p>The one with the problem meter movement is probably your spare parts meter. Just for yuks, look closely at the needle, and see if it's possibly bent and rubbing again...
by Chris Foley
Mon Sep 22, 2003 6:59 pm
Forum: General Discussion
Topic: device 74HC595
Replies: 5
Views: 1481

Re: device 74HC595

Chris nailed everything. 10.0. (Good article!) Something like this has happened to me with other parts for another reason, too. When the assembly stops being an engineering project (shoot the engineer and ship the product, for pity's sake!), people in purchasing start trying to save money. Possibly ...
by Chris Foley
Sun Sep 21, 2003 6:24 pm
Forum: General Discussion
Topic: Back-to-back Capacitors
Replies: 12
Views: 3056

Re: Back-to-back Capacitors

Hi, Bob. There are a number of good sources on the web about control loops, and particularly PID (proportional - integral - derivative) loops, which I think would probably help you. From what you're saying, it may be that having a very long time period may not help you achieve stable temperature, bu...
by Chris Foley
Thu Sep 18, 2003 8:32 pm
Forum: General Discussion
Topic: Back-to-back Capacitors
Replies: 12
Views: 3056

Re: Back-to-back Capacitors

A bit of a math error on the last post -- a tau R*C time constant of 60 seconds with a 60 Meg resistor (6 X 10M, 1W in series) would give you a C of 1 uF, not 0.1 uF. You might want bump up the resistor to 110 M (11 ea. 10 Meg 1W carbon film in series) and halve the cap to 0.56 uF. Mouser 5989-100V....
by Chris Foley
Thu Sep 18, 2003 8:53 am
Forum: General Discussion
Topic: Back-to-back Capacitors
Replies: 12
Views: 3056

Re: Back-to-back Capacitors

Hi, Bob. Placing two polarized electrolytics back-to-back can lead to reliability problems. It's been done, but the caps generally don't like it, and your actual combined impedance starts to look like an electrolytic in series with a fairly mushy voltage- and temperature-dependent resistor. Not much...
by Chris Foley
Wed Sep 17, 2003 8:50 pm
Forum: General Discussion
Topic: Need to reduce 4 volts to 3 volts
Replies: 9
Views: 2642

Re: Need to reduce 4 volts to 3 volts

Hi. From the way I read your problem, you're concerned about the power being wasted by a series resistor. If you're using 1A from a 4V source, the current will pass through both your series resistor and the load. That means you will be wasting about 25% of the power output of the battery, and would ...
by Chris Foley
Fri Sep 12, 2003 4:16 am
Forum: General Discussion
Topic: A cooling system for a cooling system???
Replies: 3
Views: 994

Re: A cooling system for a cooling system???

Hi, Ryan. Actually, you're considering a cooling system (H2O) for a cooling system (Peltier junction cooler) for a cooling system (heat sink). Water cooling of heat sinks is an ultra-efficient, if somewhat cumbersome, way of cooling semis. It's used frequently in very high power systems.<p>Now, here...
by Chris Foley
Wed Sep 10, 2003 8:14 pm
Forum: General Discussion
Topic: de-encoding a cuecat?????
Replies: 2
Views: 842

Re: de-encoding a cuecat?????

I think the information you need is at<p>How to Neuter a :Cat<p>You might also want to look at the web site<p>Overclocking the Cue Cat<p>ROTFL :-)
Chris<p>[ September 10, 2003: Message edited by: Chris Foley ]</p>
by Chris Foley
Fri Sep 05, 2003 9:45 am
Forum: General Discussion
Topic: homemade switchboard
Replies: 5
Views: 1968

Re: homemade switchboard

It's possible the "cheapest" homemade system might not be homemade at all. As small businesses upgrade their switching systems, they scrap out their old phone systems. Might want to look there -- you could get something for a song that could allow you to have intercom capability and a lot of other f...
by Chris Foley
Fri Sep 05, 2003 9:30 am
Forum: General Discussion
Topic: battery cables
Replies: 7
Views: 1707

Re: battery cables

By the way, be sure to rinse well if you use any baking soda or other chemistry on the copper wires. Residues are definitely non-conductive, and can combine with crud in the air to increase oxidation rates. After you're done, there's nothing like the good ol' wire brush to finish the job.
by Chris Foley
Thu Sep 04, 2003 5:24 pm
Forum: General Discussion
Topic: high voltage trigger/ ignitor circuit
Replies: 5
Views: 1313

Re: high voltage trigger/ ignitor circuit

You might get a spark coil from an older ('60s or early 70s) compact car. I suppose a coil might be considered a little big, but it's cheap and it'll definitely do the job. You can scrounge the HV wires and a few of the plugs along with the coil for 10 bucks or so at a scrap yard, and then you can t...