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  1. HarryA1

    555 push pbutton

    Two things from your circuit are the 20k ohm potentiometer and the 10k resistor at pin 2. The potentiometer going from 0 to 20k ohms can produce a wide range of outputs in time/widths. So the RC circuit must charge above 4 volts fairly fast to accommodate the shortest output and while charging...
  2. HarryA1

    555 push pbutton

    What you want to know is will the capacitor charge to above 1/3 of Vcc within the period of the 555 pulse; thus it will not get re-fired. Using: You get 405 microseconds,  See: http://mustcalculate.com/electronics/capacitorchargeanddischarge.php And will discharge to 4 volts from 12 volts...
  3. HarryA1

    555 push pbutton

    I am lazy and use one of the numerous online calculators like: http://referencedesigner.com/rfcal/cal_05.php
  4. HarryA1

    555 push pbutton

    In the photo the yellow trace is pin 2 (trigger) and the blue trace is pin 3 (output). Starting on the left pin 2 is at the Vcc voltage of 12 volts (0 is at the bottom of the screen) . Pin 3 is at 0 volts. On switch closure pin 2 drops to  near 0. And pin 3 rises to near 12 volts. The switch is...
  5. HarryA1

    555 push pbutton

    Try putting a resistor and capacitor in parallel after the switch. The capacitor will pull pin 2 down until it charges through the upper  10k resistor. The resistor in parallel   with the capacitor will discharge the capacitor during the period the switch is open. Do you need help with the...
  6. HarryA1

    RF Wireless Charging Technology

    It is interesting to look at their patents: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=0&f=S&l=50&TERM1=Energous+Corporation&FIELD1=AANM&co1=AND&TERM2=&FIELD2=&d=PTXT
  7. HarryA1

    RF Wireless Charging Technology

    Over the air wireless charging transmitter.  Nikola Tesla would be proud of them. see:  https://www.energous.com/company/about-energous/ Energous stock traded at a volume of 123,210,608 shares today; the average trade per day is 671,390. Symbol is : watt
  8. HarryA1

    Design real time temperature monitoring

    I do not know the PIC micro-controller so I can not help you directly. But there are videos on youtube that  maybe helpful. for example: https://www.youtube.com/watch?v=yreD5sj-i80 Also for the basic calculations see: https://www.instructables.com/id/NTC-Temperature-Sensor-With-Arduino/ Good...
  9. HarryA1

    5S3P Series parallel reverse polarity protection ?

    Yes, you would want the diode across the cell not in series thus they would only conduct on reversed voltage. Your cells are connected in parallel due to the interconnectors thus I see no way to monitor the voltage of individual cells.
  10. HarryA1

    5S3P Series parallel reverse polarity protection ?

    Are the leads from R13, R14, & R15 shorted by the interconnections between B10, B11, & B12 ? As the fuses interconnect them. I do not understand why, in say laptop batteries, the cells are interconnected that way. Perhaps for balance charging? It is common practice to put a diode around...
  11. HarryA1

    External Telephone bell as an alarm

    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...
  12. HarryA1

    5S3P Series parallel reverse polarity protection ?

    See "PCB Protection Board For 18650 Li-ion Lithium Battery Cell " https://www.ebay.com/itm/2S-3S-4S-6S-BMS-PCB-Protection-Board-For-18650-Li-ion-Lithium-Battery-Cell-US/283479999258?ssPageName=STRK%3AMEBIDX%3AIT&var=584554774361&_trksid=p2057872.m2749.l2649 Also see "Build a 2S Li-ion...
  13. HarryA1

    5S3P Series parallel reverse polarity protection ?

    Do you need reverse polarity protection only when in use?  As I take the batteries out of my camera to charge them. Only when you are charging the batteries? Or both?
  14. HarryA1

    Amplifier based on mosfet

    What type? Voltage Amplifiers: Power Amplifiers: Class A, B, AB, & C Audio Frequency Amplifiers (A.F. Amplifiers): Intermediate Frequency Amplifiers (I.F. Amplifiers): Radio Frequency Amplifiers (R.F. Amplifiers):  Direct Coupled Amplifiers (DC Amplifiers): Ultrasonic...
  15. HarryA1

    String lights in resin lamp

    If you could make a slight indentation or groove  at the wires with a Dremel like power tool perhaps you could fill it with  conductive epoxy?  Silver based epoxy is best but expensive. For insight into  conductive epoxies see: https://www.permabond.com/2016/07/26/electrically-conductive-adhesives/
  16. HarryA1

    DC Electronic Load

    There are dc electronic dummy loads reviewed on youtube.com  if that is helpful. They run 200v, 20A, and 180watts. For example see: https://www.youtube.com/watch?v=bx74sNFQvwc 
  17. HarryA1

    In the bowels of: Sonic Sensor

    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...
  18. HarryA1

    In the bowels of: Sonic Sensor

    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...
  19. HarryA1

    LED Voltage

    White LEDs are typically 3.6 volts and 20ma each. So for the 6 LEDs you would need in the order of 21.6 volts and 20ma. You could try two 9 volt batteries as a test. You can connect two batteries head to head with the + to - connectors. For insight on testing LED strips with batteries  see...
  20. HarryA1

    Burnt Resistor

    Also see: https://www.fixya.com/support/t8108170-click_multi_functional_rechargeable for more discussions on the rechargeable torch..
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