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  1. Herman the German

    Voice record/playback design help

    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...
  2. Herman the German

    Measuring roller skate wheel rotation

    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...
  3. Herman the German

    Interfacing hall-effect sensor to embedded CPU

    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...
  4. Herman the German

    Solenoid driver circuit

    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
  5. Herman the German

    newbie

    Hi cuaytech, welcome to the forum. We're glad to share our knowledge and experience with you. HtG
  6. Herman the German

    My own PSU-PCB (30 VDC / 0.002-3 A PSU REV2) [WIP]

    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
  7. Herman the German

    Please help me with High Low voltage cutoff with time delay

    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
  8. Herman the German

    Electric Fence Indicator/Display.

    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...
  9. Herman the German

    MOVED: Controlling current through relay coils with resistors.

    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
  10. Herman the German

    Electric Fence Indicator/Display.

    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...
  11. Herman the German

    Electric Fence Indicator/Display.

    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...
  12. Herman the German

    Detecting air flow

    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
  13. Herman the German

    Light bulbs

    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...
  14. Herman the German

    Sourcing ACS758 hall effect current sensor

    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.  ;D
  15. Herman the German

    Reset on 2-digit LED counter

    Hi James, basically every counter has a reset input pin. Just from a photo I can't tell what kind of counter IC is used. May be you'll obtain a schematic if you purchase the kit. If you do so post the schematic her for further assistance. HtG
  16. Herman the German

    The flashing Heart(i have some doughts)

    I just counted the number of LEDs in that piece of junk. There are 42 red LEDs (forming the heart) , 84 yellow LEDs (forming the frame) and 16 green LEDs (for the letters "I" and "U" (btw. wrong English: You starts with "Y"  ;) ). Considering that half of the 84 yellow LEDs are on at a time...
  17. Herman the German

    is there any type of sensor that . . .

    Hi vannic, I'd go one further step and check the leverage going into the gear box. There should be a distinctive (relatively) long way of the push/pull rod. Reed switches are a bit large to sense different gears. Using a Hall sensor (TLE4905) you can place them narrow enough to avoid false...
  18. Herman the German

    wind/solar charge controller

    Hammer it!  ;D
  19. Herman the German

    final year project: a blind stick that uses different sensors, help needed

    A very interesting task, indeed. I'm missing an important point. How will the user determine the relative direction of an obstacle? Telling me he will by using the stick you might as well forget about it. Many blinds have used a stick (and a specially trained dog) - consequently there is no...
  20. Herman the German

    AC Motor

    Use a snubber circuit. That way you won't have to sense EMF. HtG
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