Search found 134 matches

by Chris Foley
Fri Feb 13, 2004 6:01 pm
Forum: General Discussion
Topic: snubering a triack
Replies: 5
Views: 1685

Re: snubering a triack

If you're using anything like the MOC3010 opto-triac to drive another triac, you can use the solid-state relay circuit shown on page 5 of this Fairchild app note -- this exact circuit has worked for me on several occasions, if you're not driving a *very* inductive load (if you're driving 120 VAC loa...
by Chris Foley
Sat Jan 17, 2004 11:53 pm
Forum: Robotics
Topic: More?? - How PWM Works?
Replies: 6
Views: 3412

Re: More?? - How PWM Works?

Hi, Dale. While there are a number of other factors that you could take into consideration, generally you just say that a frequency which is too low will result in mechanical resonances/excess noise, and a frequency which is too high will result in too much lost power from the switching transistors/...
by Chris Foley
Sun Jan 11, 2004 4:53 pm
Forum: General Discussion
Topic: Need Ideas For Encasing Projects
Replies: 3
Views: 1101

Re: Need Ideas For Encasing Projects

Hi, Scott. Radio Shack has a variety of soft thermoplastic boxes which I use for knock-offs. Here are some of the tools I'll use:<p>* A pin vise and a couple of small drill bits * A drill of some kind (for plastic/thin aluminum, hand drills work pretty well) * A Uni-Bit(R) and a spare drill chuck or...
by Chris Foley
Tue Jan 06, 2004 1:15 pm
Forum: General Discussion
Topic: Need Advice on Multimeter purchase
Replies: 16
Views: 4198

Re: Need Advice on Multimeter purchase

Hi. This topic was covered several months back under the heading<p>Buying a digital multimeter<p>Good luck.
Chris<p>[ January 06, 2004: Message edited by: Chris Foley ]</p>
by Chris Foley
Thu Jan 01, 2004 6:06 pm
Forum: General Discussion
Topic: Kodak Photo Resist (KPR)
Replies: 8
Views: 3750

Re: Kodak Photo Resist (KPR)

Sorry not to get back to you quickly. You can't pour used ferric chloride down the drain because of the copper you etched out -- it's in solution, and causes problems with your local sanitary district settling tanks, even in very minute concentrations. If you live in a rural area and use a septic ta...
by Chris Foley
Wed Dec 24, 2003 1:01 pm
Forum: General Discussion
Topic: a.c. relays
Replies: 9
Views: 2470

Re: a.c. relays

Google AC Relay Shading Ring for more information -- that's what the ring is usually called.<p>Good luck.
Chris
by Chris Foley
Tue Dec 23, 2003 7:08 am
Forum: General Discussion
Topic: Kodak Photo Resist (KPR)
Replies: 8
Views: 3750

Re: Kodak Photo Resist (KPR)

I used the KPR process for etching several years back. When applying the photoresist to absolutely clean copper, I had the best luck either spraying (don't breathe in the mist -- use a very well ventilated workspace, and use a respirator) or just cutting the KPR with KPR thinner, and pouring the mix...
by Chris Foley
Sun Dec 21, 2003 5:12 pm
Forum: General Discussion
Topic: TV as an Oscilloscope
Replies: 13
Views: 3518

Re: TV as an Oscilloscope

Dean is right. It sounds like the 475/475A is your best bet. Much better than the newer 2465, which has some parts availability/obsolescence issues. Good hunting.<p>Chris
by Chris Foley
Sun Dec 21, 2003 5:01 pm
Forum: General Discussion
Topic: TV as an Oscilloscope
Replies: 13
Views: 3518

Re: TV as an Oscilloscope

Hi, Mike. A TV is too slow. The PC trick you're talking about is actually using the sound card input as a digitizing oscilloscope, with the display generated through a PC program and displayed on the monitor. There are shareware programs out there to do this, but alas, again way too slow.<p>The way ...
by Chris Foley
Tue Oct 28, 2003 9:15 pm
Forum: General Discussion
Topic: Building split power supply - can't find regulator chip
Replies: 7
Views: 1893

Re: Building split power supply - can't find regulator chip

<quote>What are the different types of supplies? Right now I use a 48VCT transformer, a rectifier and 2 1000uf caps.<p>You definitely need more capacitance. The "rule of thumb" is that, for a power supply with 120Hz ripple, you need 8300uF to keep the ripple down to 1V for every amp of current. That...
by Chris Foley
Thu Oct 16, 2003 8:23 am
Forum: General Discussion
Topic: dome light circuit
Replies: 24
Views: 5234

Re: dome light circuit

You're going to need a lot more than 10,000uF to keep that lamp on for any significant amount of time.<p>Most dome lights have a switch on their base to bypass the door switch and turn the light on. You might want to look at picking off the door switch signal, and using power from the switch "Always...
by Chris Foley
Wed Oct 08, 2003 10:03 pm
Forum: General Discussion
Topic: Hall Effect current measurement?
Replies: 3
Views: 1218

Re: Hall Effect current measurement?

Allegro makes a line of Hall effect current sensors which are good at measuring both DC and AC currents, with a bandwidth well into the audio range. They work, they're easy to use, and they're less than $10.00 USD each in single quantity from Newark. They have current sensors which have 50, 75 and 1...
by Chris Foley
Tue Oct 07, 2003 11:42 am
Forum: General Discussion
Topic: Photo_Resistor
Replies: 8
Views: 2452

Re: Photo_Resistor

If you're just looking for something to experiment with, Radio Shack has a multi-pack of photocells for a couple of bucks (276-1657). Not so tightly spec'ed as some others, but they make up for it with quantity. Here's the RS data sheet...<p> RS 276-1657 data sheet.htm <p>Photoresistors have a frequ...
by Chris Foley
Mon Oct 06, 2003 8:11 pm
Forum: General Discussion
Topic: what can I use a 13CW4 for?
Replies: 4
Views: 1404

Re: what can I use a 13CW4 for?

The 13CW4 is a Nuvistor, made by good ol' RCA. Here's a sheet on the parts:<p>History of Nuvistors<p>[ October 06, 2003: Message edited by: Chris Foley ]</p>
by Chris Foley
Fri Oct 03, 2003 6:23 am
Forum: General Discussion
Topic: lowering the output voltage question
Replies: 3
Views: 1022

Re: lowering the output voltage question

If you're not interested in high speed, your best/cheapest choice would be the CD4504 CMOS Hex Voltage-Level Shifter for TTL-to-CMOS or CMOS-to-CMOS Operation. It will work well for one-way translation of 5V logic signals (either TTL or CMOS) into CMOS-level signals. On the chip, connect Vcc to your...