Search found 26 matches

by bruinbear714
Tue Oct 14, 2003 4:35 pm
Forum: General Discussion
Topic: Printed circuit photoresist
Replies: 2
Views: 1128

Re: Printed circuit photoresist

I think he's looking for the photo resist chemical itself... Radio shack (and other electronic stores) sell pre-sensitized panels, developer, and etchant as a kit, but its expensive.<p>Look online, they are everywhere. www.injectorall.com is a place.
www.mgchemicals.com is another place.
by bruinbear714
Thu Sep 25, 2003 11:26 am
Forum: General Discussion
Topic: PCB developing
Replies: 6
Views: 2197

Re: PCB developing

There are two types of pre-sensitized pcbs, positive and negative. The positive pre-sensitized pcb is just what it says - what you see on the transparency is what you are going to get on your pcb after it is developed. The negative works vice-versa.<p>Now, with that said, you can print out your pcb ...
by bruinbear714
Fri Aug 29, 2003 10:18 am
Forum: General Discussion
Topic: Debouncing Switches
Replies: 7
Views: 3502

Re: Debouncing Switches

Yes, you can do it in a crude way in the software...<p>btfsc PORTA, 0
call MyFunction
rest of code<p>
MyFunction
some code here
btfsc PORTA, 0
goto $ - 0x01
return
by bruinbear714
Tue Aug 26, 2003 3:28 pm
Forum: General Discussion
Topic: Measuring Resistance
Replies: 15
Views: 6171

Re: Measuring Resistance

This shouldn't be too difficult.<p>Since 1V = 1000 ohms, 8V = 8000ohms, you need a current source of 1V/1000 = 1mA.<p>That can be done minimally with a pnp transistor and two resistors. One goes to emitter and Vcc, the other goes to base and ground.<p>Then your current source equation would be I ~=V...
by bruinbear714
Fri Aug 15, 2003 2:35 pm
Forum: General Discussion
Topic: PCB Layout, Strategies
Replies: 3
Views: 2059

Re: PCB Layout, Strategies

Thanks.<p>[ August 15, 2003: Message edited by: Lien ]</p>
by bruinbear714
Thu Aug 14, 2003 9:44 pm
Forum: General Discussion
Topic: PCB Layout, Strategies
Replies: 3
Views: 2059

PCB Layout, Strategies

Are there any good books or sites on the net that give advice on PCB layout for best performance and minimal EMI noise for a switching power supply?<p>Also, is there info on analog circuit pcb layout in general?<p>I am getting more switching noise/ground problems on my switching supply than I expect...
by bruinbear714
Fri Aug 01, 2003 9:00 am
Forum: General Discussion
Topic: Buying a digital multimeter
Replies: 16
Views: 3965

Re: Buying a digital multimeter

If you are just using it for hobby use and whatnot, then a cheap $5 meter would do... but if you're are involved in the ee field, then I would recommend a mid-level Fluke meter. Not only are they much more accurate, they also are well designed, have a host of USEFUL features, and the batteries on th...
by bruinbear714
Fri Jul 25, 2003 9:34 am
Forum: General Discussion
Topic: Question about previous question
Replies: 6
Views: 1953

Re: Question about previous question

Yes, there's a product called Press-n-Peel that'll let you make PCBs with a laser printer. I've used it for simple projects and it works great, but with pcb tracks and spacing less than 20mils, you could have problems.
by bruinbear714
Fri Jul 25, 2003 9:32 am
Forum: General Discussion
Topic: Need help with DC-DC conversion
Replies: 11
Views: 2609

Re: Need help with DC-DC conversion

Stephen pretty much hit the nail on the head.<p>To generate the PWM needed to drive the FETS, I would look into a TL494, or SG3525 IC. Easy to setup, easy to use, and easy to interface. Since you will most likely parallel a few FETS or use a big FET, I would look into a gate driver like an IR2110 to...
by bruinbear714
Tue Jul 15, 2003 12:58 pm
Forum: General Discussion
Topic: AC/DC conversion to simulate car voltage
Replies: 2
Views: 1143

Re: AC/DC conversion to simulate car voltage

Since you didn't specify any requirements on the 12VDC power supply, I'll just say go buy one.<p>Edit: Nevermind, I didn't read your quote carefully... anyhow, take a look at linkswitch IC's, LNK501 and LNK500.<p>[ July 15, 2003: Message edited by: Lien ]</p>
by bruinbear714
Tue Jul 15, 2003 9:04 am
Forum: General Discussion
Topic: ac/dc conversion and regulation
Replies: 12
Views: 3519

Re: ac/dc conversion and regulation

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by IRONMAN: I agree with chris, the I.C. regulators are usually the cheapest most reliable way to go, however if you're talking about 24 VAC then be careful becuase when you run that through a bridge ...
by bruinbear714
Fri Jul 11, 2003 9:40 am
Forum: General Discussion
Topic: Which Micro Controller to Choose?
Replies: 9
Views: 2766

Re: Which Micro Controller to Choose?

I gotta vote for Microchip also... the development platform for it is CHEAP and there are tons of resources available.<p>You can get a programmer for PIC chips for under $30. You can buy those chips at digikey for about $5 a pop.<p>The only difficult part is learning how the device works and its ins...
by bruinbear714
Thu Jul 10, 2003 4:32 pm
Forum: General Discussion
Topic: Amp crossover
Replies: 15
Views: 4112

Re: Amp crossover

I'm designing and building an active 3rd order lowpass crossover for my subwoofer... it'll be adjustable for -3dB between 42Hz and 75Hz without affecting the Q too greatly. Of course, I can tailor the adjustment range to anyone's liking. If you're interested, shoot me an email. I have the majority o...
by bruinbear714
Thu Jul 03, 2003 9:19 am
Forum: General Discussion
Topic: One-shot design needed
Replies: 3
Views: 1210

Re: One-shot design needed

I don't have my magazine in front of me, but in this month's issue of Nuts & Volts, there is a section on transistor circuits. In it, there are a few oscillator circuits that uses discrete devices, I believe with two transistors, a couple of caps and a couple of resistors.<p>Or you might want to loo...