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Posts posted by HarryA

  1. You can get a 120 volt to 48 volt transformer for about 15$ off Ebay. That still leaves you with 60 hertz which would be expensive to converter down in frequency. Perhaps 60 hertz  would work? I used a pocket am/fm radio for a signal device; just opened the lead to the battery for external connections. You can get one for 10$.

  2. What type?

    1. Voltage Amplifiers:
    2. Power Amplifiers: Class A, B, AB, & C
    3. Audio Frequency Amplifiers (A.F. Amplifiers):
    4. Intermediate Frequency Amplifiers (I.F. Amplifiers):
    5. Radio Frequency Amplifiers (R.F. Amplifiers):
    6.  Direct Coupled Amplifiers (DC Amplifiers):
    7. Ultrasonic Amplifiers:
    8.  Wideband Amplifiers: 
    9. Video Amplifiers:
    10. Buffer Amplifiers:
    11. Operational Amplifiers:
  3. An experimental blind spot monitoring (BSM) for an automobile. One can attach the sonic sensor on the rear
    section of the automobile. I mounted mine on the flap door that covers the gasoline cap. I used a length of
    good duct tape that wrap around the inside of the flap door also.

    I ran a length of 4 wire telephone cable from the sensor through the backdoor gap into the backseat. Then a
    length of 2 conductor wire from the Arduino Uno to the dash for a white LED. The LED has an 68 ohm resistor in
    series with it. The LED and resistor lives in the plastic tube

    For the Arduino Unio one can control the LED blinking without using the Delay() by:

    • int iLEDstate = LOW;               // used to set the LED state
      const long lInterval = 1000;       // interval at which to blink (milliseconds)
      unsigned long lPreviousMillis = 0; // will store last time LED was updated
      int iDashLED = 10;    		   // LED on/off pin
      pinMode(iDashLED, OUTPUT);
      //only distances more than 3 ft and less than 12 ft
      if(lInches > 36 && lInches < 144 ) 
          Dash_LED_Blink();  //blink the LED
      else if (iLEDstate == HIGH) 
          iLEDstate == LOW;
          digitalWrite(iDashLED, iLEDstate); //make sure LED is off
      void Dash_LED_Blink()
        // check to see if it's time to blink the LED
         unsigned long lCurrentMillis = millis();
        if (lCurrentMillis - lPreviousMillis >= lInterval) 
          // save the last time the LED blinked
          lPreviousMillis = lCurrentMillis;
          // if the LED is off turn it on and vice-versa
          if (iLEDstate == LOW) 
            iLEDstate = HIGH;
            iLEDstate = LOW;
          // set the LED with the iLEDstate 
          digitalWrite(iDashLED, iLEDstate);



  4. In the photography is the "Ultrasonic HC-SR04 distance measuring transducer sensor".

    "HC-SR04 consists of ultrasonic transmitter, receiver, and control circuit. When triggered it sends out a series of 40KHz ultrasonic pulses and receives echo from an object. Power supply: 5V DC; quiescent current: less than 2mA; effectual angle: less than 15°; distance: 2cm - 500cm."  

    The sensor is 1.75 inches/ 4.45 cm by 0.75 inches/ 1.9 cm. The IC on the bottom left is an LM324 quad op amp. The two on the right are not marked.





    small 3650.JPG

    // The sensor is triggered by a HIGH pulse of 10 or more microseconds. Give a short LOW pulse beforehand to ensure a clean HIGH pulse:

    • digitalWrite(iTrigPin, LOW); //pin 12 Out
    •  delayMicroseconds(5);
    • digitalWrite(iTrigPin, HIGH);
    • delayMicroseconds(12);
    • digitalWrite(iTrigPin, LOW);

       // Read the signal from the sensor: a HIGH pulse whose  duration is the time (in microseconds) from the sending  of the ping to the reception of its echo off of an object.

    • pinMode(iEchoPin, INPUT);   //pin 13 In
    • lDuration = pulseIn(iEchoPin, HIGH);

    The photography shows the trigger pulse in blue and the signal from the sensor in yellow bracketed by the white cursors. In the lower right is the width of the pulse: 24.4 ms from a object at 16 inches/ 40.6 cm from the sensor.






    small F3638.JPG

    // Convert the time into a distance - long way for clarity

    • lCM = (lDuration/2) / 29.1;     // Divide by 29.1 or multiply by 0.0343
    • lInches = (lDuration/2) / 74;   // Divide by 74 or multiply by 0.0135

    So for 2440 us/2 = 1220/74 = 16.48 inches  or 1220/29.1 = 41.9 cm


  5. Can you connect a 240v buzzer to the relay and get what you need? I don't know the circuit so I can not help much. Perhaps someone more knowledgeable will come along. I would think that the lead from the mains/transformer to the relay would be from the lead that has the fuse and power switch on it.

    The URL is here: https://www.electronics-lab.com/project/darkroom-timer-v2-0a-for-pcb-exposure-box/

    What does this circuit do that a 60 minute egg timer could not do?

  6. The LEDs flash alternating. The flash rate is determined by C1 and R4. There are online calculators for determining these values. Just supply power for the hazard signals.

    Supplying power and disabling one or the other LED for the turn signal.  Redraw the circuit with circuitlab  and add a DPDT switch with center off perhaps for the turn signal.


  7. You should draw the fuse F1 as a blown fuse, you have a short circuit by the wire/conductor on the right. That was a test right? To see if anyone really looked at it 😉   Isn't the 7805 a voltage regulator? Not a flasher?

    What are the" flashers" connected to? Shouldn't they connect to the anode leads of the  LEDs rather then the LEDs connecting to the Low Beam Terminal?

    What happens when the left and right flashers and the hazard flashers are on at the same time? Maybe okay. Could the DPDT switch be replaced with a SPST switch?  Also on your SPDT there is no off position.

    Otherwise the schematic  looks better than my poorly hand drawn schematics.

  8. small3571.JPG

    In the photography is the remote control receiver module from a VIZIO television.
    At the lower center is IR sensor and to the right of the sensor marked by red is the power on white LED.

    This photography shows the output from the module  when a remote control button is pressed
    and held. The burst of pulses identifies which button was pressed. Following this burst
    are the Keep Alive Pulses (KAP) - my designation.

    As long as a button is held down this train of pulses are produced.
    Used for example when changing the audio volume. The KAP are 10.5ms wide and spaced every 107ms.


    A simplified overview of a circuit I used to control a small gearhead motor. The KAP are feed to
    a 555 timer (as a monostable) that produce larger positive pulses. A leaky capacitor integrates
    the pulses that drive a transistor to power a DPDT relay.

    The relay's NC contacts powers the motor CCW until a mercury switch switches the power off.
    When a signal is received the relay switches the NO contact to closed, then the motor rotates
    CW until power is switched off by a second mercury switch.

    When the remote button is released the relay transitions and the motor rotates back CCW to its
    starting position. The mercury switches are mounted 90 degrees apart on a disk being rotated
    by the motor.


  9. The photographs show the working end of a 24 inch LED tube light. This type of light only requires
    connections to one end.

    No ballast is required for this light. The light yellow device at the lower right is the transformer.
    Next to it is a yellow capacitor. On the bottom the larger three leaded component is labelled: SDL2N65UZ.  



    There are 72 LEDs in the strip. The LEDs are arranged in pairs in parallel so there are 36 pairs in each

    strip. An 82 volt battery will light the first 30 pairs with a current of 44.9 milliamperes.
    White LEDs are rated 3.6 volts at 20 milliamperes.



  10. For those who have not peeked in to a laptop battery the photo shows the interior of one.
    The battery is made up of 6 lithium ion cells of 3.7 voltages each in three pairs.
    Connected to each pair are connections for balanced charging. This battery does not have
    thermistors for monitoring temperature during charging as some do.

    At the upper left is a larger SMD IC that is most likely the processor or brains of the battery.
    To the right of the IC is a tan rectangle with a red dot on it. This is a switch that can be
    press through the case. It is used to display the status of the battery by the 5 LEDs just to
    the right of the switch at the upper edge of the PCB. There are 2 more SMD ICs at the upper right.



  11. For you folks that have not worked on a gas range /kitchen cook stove. In the photo the igniter at the top draws
    current through the gas valve below. The igniter draws current slowly at first as it heats up to typically 3.5 amperes.
    Only then does the heater (white windings) in the valve heat the bimetallic strip. It then rises upward uncovering the
    output port normally covered by the silicone round pad on the right.  Thus the gas valve can only allow gas to  
    flow into the burner if the igniter is functioning properly.

    smallest gas.JPG

  12. I do not understand enough what you are doing to be helpful.

    Can you say, as a model, each electrode is like a wire of different metal (like copper, zinc, iron, etc) placed in an solution such that each creates a different  electromotive force (emf) or voltage. Each wire/electrode has a higher emf going from 1 to 9 perhaps?  Like  wire 1 has 0.1 mv emf, wire 2 has 0.15 mv emf, and so on.

  13. 23 hours ago, jim02ss said:

    Whats the simplest way to achieve my goals

    I would think replacing the relays. You can get a pair of Omron 24 VAC relays for  11$ off Ebay. Omron has a good rating on Amazon.com

    Else you can use a bridge rectifier to convert to cleaner (less ripple) dc. Search for "bridge rectifier diagram" for many diagrams on the  internet. A package with all four diodes in it is about 1$ on Ebay for example.


    good luck



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