Search found 55 matches

by Michael J
Sun Dec 04, 2005 3:29 am
Forum: General Discussion
Topic: circuit to energize a relay for 30 seconds
Replies: 5
Views: 1654

Re: circuit to energize a relay for 30 seconds

Even easier way, See N&V April 2005 P:50 Universal Relay. Just use the section after the OP Amp, with a momentary swith to charge the input capacitor. 2 x Resistors. 1 x Capacitor change to 33µF or 47µF Electro. 1 x MOSFET 2N7000. 1 x 1N4004 Diode, MOSFET back EMF protection. 1 x 1N4148 1 x 12V relay.
by Michael J
Sat Nov 26, 2005 5:04 am
Forum: General Discussion
Topic: IR sensor
Replies: 23
Views: 4167

Re: IR sensor

The pyro sensors used in motion detectors are very fiddly devices to use. They can be dammaged just by touching the surface of the pyro element, so they say. I had a source of used detectors/sensors from a security firm. I gave up playing with them as they need very specific circuitry to get them to...
by Michael J
Wed Nov 16, 2005 11:24 pm
Forum: General Discussion
Topic: Line monitor
Replies: 11
Views: 1945

Re: Line monitor

By the time you fiddle around trying to make something that will probably resemble a Dogs Breakfast, when finish anyway. Just get the cheapest Data Logger you can find and a small transformer, monitor the output. You could look at the Dallas/Maxim range of Logger / Temperature logger / Power logger,...
by Michael J
Tue Nov 15, 2005 10:12 pm
Forum: General Discussion
Topic: Help with electronic to electro-mechanical conversion.
Replies: 7
Views: 1598

Re: Help with electronic to electro-mechanical conversion.

A 10K NTC seems likely what it was, and 32k whith ice covering sounds about right. The values could vary from manufacturer to manufacturer slightly though. A 10K Disk NTC is a fairly common item, should be able to obtain from a good electronics supplier. If you did manage to get one that was quite a...
by Michael J
Fri Nov 11, 2005 12:49 am
Forum: General Discussion
Topic: divide by 10
Replies: 18
Views: 3735

Re: divide by 10

Matt, I should have said use an MC14060 or MC14040, shame on me.

Jimandy I saw the 74 and figured TTL.
by Michael J
Thu Nov 10, 2005 9:39 pm
Forum: General Discussion
Topic: divide by 10
Replies: 18
Views: 3735

Re: divide by 10

If you have blown up the chip get a CMOS version
next time, they work from 3 to 18V, less headaches.

You don't have to worry about grounding the unused outputs and they (O/P) will happily
drive an LED.

<small>[ November 10, 2005, 09:45 PM: Message edited by: Michael J ]</small>
by Michael J
Thu Nov 10, 2005 1:03 pm
Forum: General Discussion
Topic: divide by 10
Replies: 18
Views: 3735

Re: divide by 10

4017 is one of the most common chips on the planet.

You could try a 4040 or 4060, they divide by
4, 8, 16, 32, 64 etc.

With something like the above you can select
a different O/P for fast or slower timing speeds.
by Michael J
Thu Nov 10, 2005 12:33 pm
Forum: General Discussion
Topic: divide by 10
Replies: 18
Views: 3735

Re: divide by 10

Hi Mat, you could use a 4017 to divide by 10 or 2, 3, 4 ,5, 6, 7, 8, 9. If not by 10 just take the last output used back to pin (15 from memory) to reset the count. Whatever O/P you use via a current limiting resistor and LED to GND. 1k - 1k2 Ohms for 12V 330 - 560 Ohms for 5V <small>[ November 10, ...
by Michael J
Thu Nov 10, 2005 12:23 pm
Forum: General Discussion
Topic: Help with electronic to electro-mechanical conversion.
Replies: 7
Views: 1598

Re: Help with electronic to electro-mechanical conversion.

There's nothing special about a thermistor, they are only a resistor that changes resistance with the temperature changes. Has your thermistor got any markings ? They could be coded e.g 103, 104 etc or banded like a resistor e.g. orange body, brown band, black band, gold band = 10k. They are rated b...
by Michael J
Sun Nov 06, 2005 2:05 am
Forum: General Discussion
Topic: Fluorescent Lamp Inverter
Replies: 25
Views: 4896

Re: Fluorescent Lamp Inverter

Oatley Electronics here in Australia have done a few of these circuits in the past few years. They have made a few that will run 240V CFL tubes,(folded compact fluoroecent) they don't work with the 110V USA types as far as I know because internal diode issues etc. http://www.oatleyelectronics.com/ W...
by Michael J
Sun Nov 06, 2005 2:02 am
Forum: General Discussion
Topic: Burnt Starting Coil
Replies: 3
Views: 1221

Re: Burnt Starting Coil

<small>[ November 06, 2005, 02:03 AM: Message edited by: Michael J ]</small>
by Michael J
Sat Nov 05, 2005 12:42 am
Forum: General Discussion
Topic: piezo as an input
Replies: 2
Views: 884

Re: piezo as an input

You won't blow up either the OP Amp or Piezo if just using it on an input. It is a polarized device but will work in both directions, like a speaker. Voltage in, disk flexex one way, voltage reversed disk flexes opposite way.(as a MIC the same applies, (Try red to +non inverting i/p, 741 )) You may ...
by Michael J
Sat Nov 05, 2005 12:23 am
Forum: General Discussion
Topic: Burnt Starting Coil
Replies: 3
Views: 1221

Re: Burnt Starting Coil

The contacts should resemble the head of a rivet
etc, usually flat, they should be solid
material in a large motor, copper/silver.

A full rewind may be the way to go, but may be
costly, but should also last another 30 years
if done correctly.
by Michael J
Fri Nov 04, 2005 3:01 pm
Forum: General Discussion
Topic: headphone jack to line level
Replies: 4
Views: 1169

Re: headphone jack to line level

You may find you need to run the iPod flat out just to get enough volume to hear it at a reasonable level. The output on most of these MP3 Players is in reality very low, afterall you are virtually placing the speaker inside your ear canal. A Flea in there sounds like a herd of Elephants. Most of th...
by Michael J
Thu Nov 03, 2005 9:37 pm
Forum: General Discussion
Topic: the amazing talking coil
Replies: 7
Views: 1327

Re: the amazing talking coil

Try Fingernail Varnish.

How hot does the coil get ?