Hi nexus_2006,

you might want to try this circuit.

It is built around an ISD2532 (32seconds at 8KHz sampling frequency). If that one won't suffice you might select an ISD2564 (64seconds).

The device can be controlled locally and via a microcontroller. All necessary connections are available at SV2.

Remark: The mic connects via two pads. However if a mic with built in Fet-transistor is used polarity may be changed turning the mic 180degrees.

If you are interested in the Eagle files leave your full name and email address in a PM.

Regards

HtG

Hi Lon,

I assume the roller skates are fixed to a test stand.

Using a permanent magnet on one side of one wheel and a counter weight on the opposite side you won't have any unbalanced situation affecting bearing life time.

Use a hall switch to sense magnet passage (magnet must face the sensor with it's south pole) you can count revolutions employing a simple counter circuit.

Check out the TLE4905 for your purpose and decide if it fits your needs.

HtG

Hi stube40,

the question is: Do you really need a programmable Hall sensor for your application?

The most simple way is using 3 pin hall sensor the same way as you would use any input from a button or switch.

Check out the TLE4905 if it fits your needs.

The TLE4905 switches output to ground (L) if pulled up by a 10KOhm resistor as soon as the south pole of a magnet gets into the magnetic sensitive field.

HtG

Hi Novice1,

the type of diode used depends largely on the solenoid.

The more current the solenoid pulls the higher the EMF pulse.

For solenoids in the order of a miniature relay a 1N4148 will suffice.

For high power solenoids I recommend using Schottky diodes like SBxx.

HtG

Hi cuaytech,

welcome to the forum.

We're glad to share our knowledge and experience with you.

HtG

Hi LEECH666,

here are some numbers which should help you decide about the trace width.

All results are based on a 160mm long trace, copper weight 1oz (35

Hi sakbd.2010,

this circuit has been buried some 20 years ago.

Where did you dig it out?

There are easier and more effective circuits. Just google for them.

HtG

Hi rfranzk,

all resistors are standard 1/4W.

If you have the schematic loaded in Eagle you'll get info about every part.

Use the "I" symbol (I=info) and click the part you want to know more about.

If you click on C1 you'll get the info that it's an MKS-02 (made by WIMA). Caps are not critical in that application and you might use ceramic or polyester caps.

Tantalum and electrolytic caps are polarized and not to be used for AC which will be present at the circuit input with the shape of a pulse.

With a cheap DMM you won't be able to measure uV (0.1mV=100uV). You won't be able to measure that voltage even with a mid class DMM since it won't zero accurately.

Even with an oscilloscope you won't see any trace change in the Y-axis since most of the scopes require at least 2mV input.

Just amplify the signal and check the circuit output voltage. If it is not sufficient you might use 470K for R3 to obtain a total amplification of 1,849 (presently 1,104)

If all the changes are not successful you might increase the number of turns of the "transformer".

I haven't tested the circuit, but it should do well.

Regards

HtG

This topic has been moved to [Circuit/General Requests]. because of hijacking another thread.

http://www.electronics-lab.com/forum/index.php?topic=20960.0

Hi rfranzk,

here is a circuit with an ultrabright blue LED (KINGBRIGHT) Using an OSRAM LED reflector you should see the device flashing even at daylight.

The PCB design is purely single sided.

The amplifier has a total gain of up to 1,104 and should suffice to amplify any voltage picked up by the "transformer". It is dimensioned to amplify 0.1mV from the transformer.

For the transformer use only cable with the appropriate voltage rating.

If you are interested to obtain the Eagle files please PM me your email address.

Regards

HtG

Hi,

I do not recommend using a voltage divider to indicate a functioning electric fence.

Normal resistors are designed for a maximum voltage of 300V. Using those for a voltage divider you have to take care not to exceed the maximum allowable voltage drop per resistor.

If you are going to use neon lamps try get some rated 50V/2mA (normally built into switches of electronic kitchen appliances). 

Wind 4 to 6 turns of insulated wire around the HV-line and connect both ends of the "transformer" to the neon lamp.

You will probably not be able to see the neon lamp flash during day time, but at night it should not not be a problem over a distance of 8km - a distance you can see a cigarette end glowing.

To increase intensity of the flash you could use reflectors as they are often used for LEDs.

HtG

Hi,

you might want to try out this circuit. It uses transistors to sense airflow and its output is PWM.

If you want to obtain the Eagle files please PM me leaving your email address.

HtG

Hi KelvinIV,

there is one known and reliable method to calculate for filament resistance for me:

Measure the current flow with the lamp being supplied by its nominal voltage.

Then use Ohm's law to determine the resistance.

Filament type lamps have very low cold resistance which increases with heating.

HtG

Hi stube,

I'd try to obtain a free sample at Allegro micro.

HtG

Edit: Try to get two of them and forward one to me. I need it for emergency automatic power cutoff for my garden gate.