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  1. bertus

    Question hdd badblock interference and dvd burn

    Hello, The bad blocks are blocked for writing again. https://www.howtogeek.com/173463/bad-sectors-explained-why-hard-drives-get-bad-sectors-and-what-you-can-do-about-it/ Bertus
  2. bertus

    Question SSD china aliexpress

    Hello, What is your budget? What size of SSD are you looking for? Cheap SSD drives can be made using old technology. The old technology seems to wear-out sooner and the new ones. I would still go for major brands like Samsung, San Disk, Crucial or Western Digital. I have a 500 Gb SSD NVMe as...
  3. bertus

    Question battery lithium and polymer lithium storage

    Hello, Read this article on the Battery University: https://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries Bertus
  4. bertus

    The Theremin Stretch

    Hello, if you want to "study" on a real theremin, have a look at the theremin from Bob Moog: There is a full description based on the given schematic in this PDF: https://www.cs.nmsu.edu/~rth/EMTheremin.pdf Bertus
  5. bertus

    Russell Kirsch , the inventor of the pixel , has passed away

    Hello, The inventor of the pixel for digital photography has passed away. https://en.wikipedia.org/wiki/Russell_Kirsch Without him, digital photography would likely not have existed. Bertus
  6. bertus

    Short wave radio on breadboard

    Hello, The UA741 also shows +/- 5 volts or 10 volts as minimum power supply. Bertus
  7. bertus

    The Theremin Stretch

    Hello, Did you use the correct pin-out? Bertus
  8. bertus

    The Theremin Stretch

    Hello, The two side pins are connected together, the other pin is the other side of the capacitor: Bertus
  9. bertus

    What music do you like?

    Hello, Here is a real life version of one of the instruments that I posted from animusic: Bertus
  10. bertus

    The Theremin Stretch

    Hello, I see that the breadboarded version uses the 4 to 50 pF. You can still try the 8 to 40 pF capacitor. When it has a to low value, you can put a 15 pF fixed capacitor in parallel. Here I found a video that explains the use of a "real" (commercial) theremin: Bertus
  11. bertus

    The Theremin Stretch

    Hello, The schematic in post #3 calls for a 4 - 22 pF. You could try the 8 - 40 pF: https://secure.sayal.com/STORE2/View_SHOP.php?SKU=218582 If you can get hold of them, I would use some higher quality variable capacitors, like the ones I have here: Bertus
  12. bertus

    The Theremin Stretch

    Hello, I see the J110 at the shop. You could try that one. Bertus
  13. bertus

    Repair a Geneva Lab Model L

    Hello, That capacitor really looks bad. Here is a page how to visualy spot bad caps: https://www.robotroom.com/Faulty-Capacitors-1.html Bertus
  14. bertus

    The Theremin Stretch

    Hello, From the pages I gave you: Every NJFET with a Up between -1.5 and -3V and a Idss between 2 and 6mA should do the job. Your MPF102 shows -0.5 to - 7.5 Volts and a pich-off voltage of - 8 Volts. You can have fets in the mentioned range, but also have fets that fall outside the range. The...
  15. bertus

    The Theremin Stretch

    Hello, When there is no sound at all, I am afraid that the oscillators do not work. The working is based on the frequency difference of the two oscillators. As the oscillators should work at about 410 kHz, there is also a chance that they are to far apart in frequency and the circuit is putting...
  16. bertus

    The Theremin Stretch

    Hello, On the video you see that the theremin itself is running on +6 Volts and the LM386 is running at +9 Volts. There must be a voltage regulator that brings down the voltage from +9 Volts to +6 Volts. A LM78L06 can do this, but will only work until 8 Volts from the battery. Bertus
  17. bertus

    tinning

    Hello, Here is a funny booklet about soldering: https://mightyohm.com/blog/2011/04/soldering-is-easy-comic-book/ Bertus
  18. bertus

    The Theremin Stretch

    Hello, On the youtube page there is a link to the original schematic on thereminworld forum: http://thereminworld.com/Forums/T/29231/my-new-year-gift-to-tw Bertus
  19. bertus

    Sensistor vs Thermistor

    Hello, The KTY series from NXP seem to be the silicon PTC's like the sensistor. Bertus
  20. bertus

    Sensistor vs Thermistor

    Hello, The special semiconductor resistors are mentioned in application notes for log amplifiers. The application notes mention the Q81 resistor. Bertus
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