Search found 55 matches

by Michael J
Thu Aug 18, 2005 5:29 am
Forum: General Discussion
Topic: Dew Point
Replies: 25
Views: 3904

Re: Dew Point

Hi Bren, Years ago I described a humidity circuit in an Australian magazine.<p>The Humidity sensor I used was recovered from an old VCR tape machine,,video recorder.<p>The very early ones used a small ceramic wafer sensor, usually square or rectangular and around 3/8 to 3/4 inch in size. They were v...
by Michael J
Sat Aug 06, 2005 6:58 am
Forum: General Discussion
Topic: 2 wire foto cell question
Replies: 17
Views: 3366

Re: 2 wire foto cell question

The Universal Relay As described in Nuts & Volts
Magazine, April 2005, P: 50. can do the job,
just ad a resistor between Pin 1 and 3 on the
LM358 for extra hystersis if needed.(try 1M Ohm)
Holes are provided onboard.<p>Just a thought.
by Michael J
Thu May 26, 2005 5:14 am
Forum: General Discussion
Topic: voltage regulator circuit
Replies: 8
Views: 1738

Re: voltage regulator circuit

What's wrong with using an old PC power supply.<p>
~ ;o)
by Michael J
Sat May 21, 2005 3:18 am
Forum: General Discussion
Topic: Hex Heverter Relay activation
Replies: 14
Views: 3468

Re: Hex Heverter Relay activation

Rzimpala, You sholud look at the project Universal Relay Nuts and Volts APR 2005.<p>It will operate a relay using any voltage in the supply range, for that matter anything you can think of, transducer, mic, sensor.<p>You would need to get a suitable 5 or 6 volt DPDT relay, they are available in that...
by Michael J
Wed May 18, 2005 3:08 am
Forum: General Discussion
Topic: WATT-HOUR METER Table Lamp
Replies: 7
Views: 1584

Re: WATT-HOUR METER Table Lamp

I have heard of people many years ago trying to defraud they Electricity companies by placing a powerfull magnet in close proximity to the meter to slow it down. (they were usually caught out)<p>Try placing a small rare earth magnet around the egde of the Aluminium disk until you get a desired speed...
by Michael J
Fri May 13, 2005 2:22 am
Forum: General Discussion
Topic: DC & AC
Replies: 12
Views: 2517

Re: DC & AC

The AC is used to prevent the poles or contact points being eaten away by electrolysis.<p>"Any" DC voltage will eventually eat the electrodes to peices, with much more than about 2 Milliamps flowing it will be noticable in a few days, anything over a few hundred Milliamps you can almost see happenin...
by Michael J
Wed Apr 20, 2005 3:21 pm
Forum: General Discussion
Topic: Computer as Oscilloscope
Replies: 8
Views: 2247

Re: Computer as Oscilloscope

There are several applications around that let you use your sound card as a CRO input for your computer.<p>The limitations are as Dean and Ezpcb said 1- Bandwidth and 2-Voltage.<p>There is a project available in Australia called a "soundcard pre amp", was published in the now deceased magazine Elect...
by Michael J
Tue Apr 12, 2005 2:18 am
Forum: General Discussion
Topic: suggest a circuit to convert 24vac to 12vdc
Replies: 13
Views: 2954

Re: suggest a circuit to convert 24vac to 12vdc

A capacitor in the range of 1000 to 4700 µF should work in most cases, 63v.<p>The input of the regulator has to be 2 volts or so higher than the regulated output, while supplying the rated current load you require for it to function correctly. Otherwise they become a non regulator. Low dropout types...
by Michael J
Sat Apr 09, 2005 4:06 am
Forum: General Discussion
Topic: suggest a circuit to convert 24vac to 12vdc
Replies: 13
Views: 2954

Re: suggest a circuit to convert 24vac to 12vdc

P.S. Forgot to mention I put the resistors in
series with the 24v AC transformer output, before the Bridge Rectifier, filter cap and 7812 regulator,,, ~;o)
by Michael J
Sat Apr 09, 2005 3:32 am
Forum: General Discussion
Topic: suggest a circuit to convert 24vac to 12vdc
Replies: 13
Views: 2954

Re: suggest a circuit to convert 24vac to 12vdc

Hi all I'm new to this forum.<p>Stepping 24v AC down to 12v DC can be tricky and not as easy as you might think. A fully rectified 24v AC becomes around 36/37 volts DC no load which is very close to the recomended 40v max for most 3 terminal regulators. Depends on the transformer used. But that is u...