Search found 33 matches

by jonjonr6
Sat Oct 11, 2003 4:10 pm
Forum: General Discussion
Topic: dc desktop pc
Replies: 7
Views: 1640

Re: dc desktop pc

Dave,<p>Are you planning on installing your Mac into your car? I have already explored all the power supply possibilties when I installed a PC in my car. I eventually found it easiest to use the power invertor instead of trying to design and build a DC/DC power supply strong enough to run it. If you...
by jonjonr6
Tue Jul 15, 2003 2:01 pm
Forum: General Discussion
Topic: bad 556 timer?
Replies: 1
Views: 673

bad 556 timer?

I have been working on a 556 timer relay design. Originally tested the design with a tester circuit board. Then soldered up a permanent device. However, it appears that the trigger input is always grounded. I removed the 556 timer (socketed), and put it back in the tester board. I connected Vcc and ...
by jonjonr6
Thu Jul 10, 2003 7:34 am
Forum: General Discussion
Topic: Here's How to Solve Our money Problems!
Replies: 21
Views: 5422

Re: Here's How to Solve Our money Problems!

I read some of it, but not all. Several things stuck out to me that I did not agree with. He said, "let man rule man, not money". He very much suggests that money is basically the root of the problems. This isn't exactly true by the way I see it.<p>I think the problem is that people want to feel bet...
by jonjonr6
Mon Jul 07, 2003 9:07 pm
Forum: General Discussion
Topic: 555 timer circuit help needed
Replies: 13
Views: 2591

Re: 555 timer circuit help needed

Thanks.<p>Actually, I have never worked with or looked at flip-flops. Honestly, I "learned" (term used very loosely here) 555/556 timers just for this one project. So far, I $30 into th 556 design, and almost have it all soldered down. I'm not sure what leakage current is. I'm guessing that it uses ...
by jonjonr6
Sat Jul 05, 2003 8:56 pm
Forum: General Discussion
Topic: 555 timer circuit help needed
Replies: 13
Views: 2591

Re: 555 timer circuit help needed

ok, I built it without the extra 2k resistor and diode. I used a 556 timer, and ran the output to the trigger of the second half of the 556. It seems to work just fine. However, I've got to get the cap/resistor combination on the first hreshold/disharge so that it does about one hour. I have a 4700u...
by jonjonr6
Sat Jul 05, 2003 2:09 pm
Forum: General Discussion
Topic: 555 timer circuit help needed
Replies: 13
Views: 2591

Re: 555 timer circuit help needed

Ooops, sorry, It was supposed to go straight to the right one. Its the one titled: 555 timer Mono stable (one shot) circuit<p>There are two diagrams. The one on the right is designed for the long input. However, I'm thinking that in my situation, the 2K resister connected to the + supply and the tri...
by jonjonr6
Fri Jul 04, 2003 4:17 pm
Forum: General Discussion
Topic: 555 timer circuit help needed
Replies: 13
Views: 2591

Re: 555 timer circuit help needed

Well, obviously there are several different ways to get the same results. Here's the circuit diagram I found and was planning to use (on the left). However, he has different values for caps and resistors, and he has a diode and another resistor in his design. Are they needed?<p> http://ourworld.comp...
by jonjonr6
Thu Jul 03, 2003 11:58 am
Forum: General Discussion
Topic: 555 timer circuit help needed
Replies: 13
Views: 2591

Re: 555 timer circuit help needed

Thanks.
by jonjonr6
Wed Jul 02, 2003 12:50 pm
Forum: General Discussion
Topic: Power Supply thoughts needed
Replies: 15
Views: 3219

Re: Power Supply thoughts needed

Thanks everyone,<p>I eventually broke down and looked for the simplest solution. I ended up with a standard ATX power supply running off a DC power invertor (I already have both), and a system board that supports "last power on state" (will boot automatically when the power is reapplied). The unit w...
by jonjonr6
Mon Jun 30, 2003 5:05 pm
Forum: General Discussion
Topic: help identifying a resistor
Replies: 4
Views: 1201

Re: help identifying a resistor

Thanks. I doubt I can get the scematics for this amplifier. It's a car audio amplifier, and they typically are protective about their designs. This one happens to be an Xtant 302a. Xtant is definitely not going to give out the schematics for their gear. Since this things dead one way or another, I'l...
by jonjonr6
Mon Jun 30, 2003 12:32 pm
Forum: General Discussion
Topic: help identifying a resistor
Replies: 4
Views: 1201

help identifying a resistor

This should be very basic and easy. I need help identifying a resistor on a circuit board. I also need suggestions as to where I can buy replacements.<p>I have an amplifier that released the genie. Two power mosfets were blown. I ordered identical replacements and soldered them back in. During furth...
by jonjonr6
Sat Jun 28, 2003 9:53 am
Forum: General Discussion
Topic: Power Supply thoughts needed
Replies: 15
Views: 3219

Re: Power Supply thoughts needed

So what you're saying is, that to increase DC voltage, I'd need to use some sort of switching device to turn the DC into pulses, then pass that through a capacitor, then to a transformer (where the voltage is actually increased), then rectify it back into DC. Hence, I'm back to using my DC/AC invert...
by jonjonr6
Thu Jun 26, 2003 2:36 pm
Forum: General Discussion
Topic: MOSFET vs. Transistor
Replies: 21
Views: 3722

Re: MOSFET vs. Transistor

I'm confused again. But I guess what I was misunderstanding is that I need the transistor turned either On or Off, not partially on, or else the heat will kill it. Even with a beefy heatsink? We're talking a large aluminum heatsink if needed. And what about the high power regulators, like the ones a...
by jonjonr6
Wed Jun 25, 2003 8:33 pm
Forum: General Discussion
Topic: MOSFET vs. Transistor
Replies: 21
Views: 3722

Re: MOSFET vs. Transistor

Hmmm, I think I need more knowledge about power transistors and mosfets. There are alot of terms used (both here and while looking at component specs), and I don't know what they all mean. Obviously they have significant importance. What is the dropout voltage?<p>And what about this regulator... htt...
by jonjonr6
Wed Jun 25, 2003 6:46 pm
Forum: General Discussion
Topic: MOSFET vs. Transistor
Replies: 21
Views: 3722

Re: MOSFET vs. Transistor

The goal is to install a computer in my car. Yes, I know that 12vDC ATX power supplies are available commercially, but the cheapest is $130, and specs out at 14A and 10A on the 3.3v and 5v rails. It's not strong enough to power much more than an ITX or PII system. I originally wanted to modify an ex...