Search found 8 matches

by Bob Quale
Tue Nov 11, 2003 3:43 pm
Forum: General Discussion
Topic: Need so help with a timming circuit.
Replies: 3
Views: 1052

Re: Need so help with a timming circuit.

I thought that the 555 timers didn't like to have a steady on state at the trigger as I would be doing when I turn the switch on. The switch may be on for any lenght of time as long as it has the 15sec delay and 30sec end.<p>Thanks Bob
by Bob Quale
Tue Nov 11, 2003 6:30 am
Forum: General Discussion
Topic: Need so help with a timming circuit.
Replies: 3
Views: 1052

Need so help with a timming circuit.

I'm trying to make a 12v timer that, when a switch is turned on that will run a 12v pump, the timer will wait 15 seconds and then power on a 12v solinoid. When the same switch is turned off, the solinoid will stay energised for 30 seconds. I was tinking maybe a op amp and npn transister but can't ge...
by Bob Quale
Tue Jul 29, 2003 1:45 pm
Forum: General Discussion
Topic: Optoisolators
Replies: 9
Views: 2361

Re: Optoisolators

Thank you for all the help!!<p>I am very much a newbie. I think I will go with the H11L1. I think the best place to get it would be Digi-key? Any other coments or sugestions, I'm all ears! I can't wait to make something that is sortive complicated and works!<p>Thanks again<p>Bob
by Bob Quale
Mon Jul 28, 2003 11:01 am
Forum: General Discussion
Topic: Optoisolators
Replies: 9
Views: 2361

Re: Optoisolators

So then am I correct to think there are three leads, emiter, base and colector that are in a on or off state only? Or does the voltage at the gate vary the amount of current threw it? <p>Bob
by Bob Quale
Mon Jul 28, 2003 4:22 am
Forum: General Discussion
Topic: Optoisolators
Replies: 9
Views: 2361

Optoisolators

I need to isolate a motor driver from the parellel port on my computor. I want to use a optoisolator but don't know how they work. Can anyone help? The ones I have seen are six pin packs, transistor and Darlington output NPN. A link with good info would also be great if available. Basic circuit disi...
by Bob Quale
Sun Dec 08, 2002 1:46 pm
Forum: General Discussion
Topic: Power supplies
Replies: 9
Views: 2141

Re: Power supplies

So is it feasable to think i can buy a surplus power supply from a computor, like all electonics sells and use it? Or should I spend the extra and by a Elenco or similar. Some of the surplus ones have a minimum current rating. If i under power it what will happen? Thanks again for all the imput. <p>...
by Bob Quale
Sun Dec 08, 2002 8:00 am
Forum: General Discussion
Topic: Power supplies
Replies: 9
Views: 2141

Re: Power supplies

American sience and surplus has a supply for about $85.00. Is it worth it to build one at this cost? I would think by the time I get the transformer and other parts I would be better off buying one and get to building stuff. What is the difference between linear and swiching for practicle purposes?<...
by Bob Quale
Sun Dec 08, 2002 6:51 am
Forum: General Discussion
Topic: Power supplies
Replies: 9
Views: 2141

Power supplies

I have been watching this site for a while and have found it very informative. Now I have a question. I need a power supply for making little circuits. Digital, timer, op amp ect. I'm just learning about electronics. Can I buy a surplus swiching supply and make it variable or do I need a supply with...