Recent content by HarryA

  1. HarryA

    Power supply?

    Good points. As the power supply itself has a split power supply off the 19-19 volt windings one could "borrow" a few ma from that for experiment. Adding three terminals at the back of the case. The KBP210 bridge rectifier is rated 2.0 amperes and the 15v regulators (L7915/L7815) at 1.5...
  2. HarryA

    Power supply?

    In the schematic on the far left note the three transformer windings that supply voltage to the main circuit. There are 9v, 12v, and 16volts. The two relays connecting the windings to the bridge rectifier can supply voltages of: 12v, 21v, 28v, and 37v as required? I gather the circuit...
  3. HarryA

    Power supply?

    Both are connected to the case. I would think if you had an op amp that required both positive and negative power this power supply would not work because the yellow terminal is not a "real" ground from a power supply perspective? Open circuit the voltage between the red and yellow...
  4. HarryA

    Power supply?

    Greetings from cold Pennsylvania. I am working on a power supply that I took to be dual polarity power supply with variable output. The power supply has three terminals: red for positive, black for negative, and yellow for neutral (?). But on setting the voltage for 10 volts you get 10 volts...
  5. HarryA

    If You're an Engineer

    The part at 19.32 mins. is very true! USB plug is always wrong! If you're an Engineer..
  6. HarryA

    For Sale: Dell Latitude 3340 Laptops Windows 10

    Dell Latitude 3340 Laptop Windows 10 Clean Install NO CHARGER Priced between 50and 40 USD. Shipping is 1 cent but handling is in the order of 11$. There are about 35 of then - some company up graded to better laptops? see: Laptops Goodwill is a charity organization helping folks train for...
  7. HarryA

    For Sale: Tube tester and Hammarlund radio

    Note the receiver is Pickup Only at Southwestern Pennsylvania. ( How to you edit a previous post?)
  8. HarryA

    For Sale: Tube tester and Hammarlund radio

    GC Electronics Vintage Tube Tester Bidding ends on Aug. 14 https://shopgoodwill.com/item/238420459 Years ago I would loved to have one of these! Vintage Hammarlund HQ-170 Tube Shortwave Receiver Bidding ends on Aug. 11 https://shopgoodwill.com/item/238373131 BEWARE OF THE SHIPPING IT CAN BE...
  9. HarryA

    PCB: Free Manufacturing

    Learn how to design your own circuit boards from scratch" see:https://hackclub.com/onboard/
  10. HarryA

    For Sale: MUSICAL KEYBOARD NECK TIE

    You could be a big hit at the Christmas party! Tie
  11. HarryA

    High Voltage Direct Current

    "Propose new HVDC technology solutions to strengthen the U.S. energy grid." What are the advantages of HVDC? see:https://www.herox.com/hvdcprize?from=explore For numerous other challenges see: https://www.herox.com Select [challenges]
  12. HarryA

    Voltage Converter - Electric Heater Project

    Why not use the 'cold' water heater tank as the primary energy store itself? There are two heating elements in the tank. The top one ,for quick recovery, creates a bubble of hot water at the top of the tank. When that is hot the lower element heats the lower part of the tank. The two are never...
  13. HarryA

    PHP Web Site Counter

    Greetings. I am trying to add a counter to a web page but it is not cooperating! Directions are: place the count.php file and the hitcount.txt file on the server in the same directory as the web page. hitcount.txt file should contain a value like zero. For the include in the web page I use...
  14. HarryA

    Home brewing fermentation monitoring

    Back in the old days when folks made beer in crocks they would hold a burning match over the surface of the beer. If the match went out the beer was still brewing. Thus producing carbon dioxide. There are carbon dioxide sensors for the Arduino.
  15. HarryA

    define a variable in header file

    Does this help? Using Arduino C code; /// file to be included #ifndef _TEMP_H #define _TEMP_H extern int a = 10; #endif //in main code file #include "temp.h" void setup() { Serial.begin(9600) ; //used to display results } void loop() { //display a Serial.print(" int a = ")...
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