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  1. (*steve*)

    Series Parallel Problem

    Since we can't see your circuit we can't tell. A simple general solution is to find a pair of resistors either in series or parallel and replace then with a single resistance of the calculated combined value. Repeat this process until there is only one resistor left. There are circuit...
  2. (*steve*)

    LED help

    Aaaagh, even 1W LEDs need heatsinks if you want them to have a normal life. And placing LEDs in parallel is far worse if they are not thermally connected (it's not a great idea even then, unless you can be assured that they are fairly closely matched). And, it's better to use a constant...
  3. (*steve*)

    Small SMD Fell Off Motherboard

    If it's a capacitor, and if it came from where you think it did, then it's likely to be a decoupling capacitor. These are generally used in abundance, and the loss of one or two is unlikely to have any impact. There is a recent video of a person removing all the decoupling capacitors from a...
  4. (*steve*)

    Charge time for lithium batteries

    1.3Ah :-)
  5. (*steve*)

    Buck Converter with PİC16F877A

    I also don't have much time. The difficulty reading your schematic probably exceeds that in finding the problem. I'm happy to help, but I'm not prepared to redraw your schematic. Who knows, maybe your poor drafting skills are hiding an obvious error that you could spot of your schematic...
  6. (*steve*)

    Amateur (Ham) Radio and RC (Radio Controlled) Flight

    I would not like to be in a 737 if a collision resulted in an uncommanded and asymmetric retraction of leading edge devices in a critical phase of flight. I think it's undisputable that even a recreational quadcopter has the potential to penetrate an aircraft. The fact is that if you're flying...
  7. (*steve*)

    Buck Converter with PİC16F877A

    Can you clean up your schematic first? See here. edit: I would also add: Draw your batteries up the same way (+ve to the top is conventional) Don't draw long lines to ground symbols. Insert a new one.
  8. (*steve*)

    NSW Australia summer road trip

    Are you planning to visit Carnarvon for July 20-21 2019? It's not summer, but it may as well be :-)
  9. (*steve*)

    Amateur (Ham) Radio and RC (Radio Controlled) Flight

    Even smaller ones are potentially There is an excellent video of the effect a small "recreational" quadcopter can have on the leading edge of an aircraft wing when the collision happens at the speed that commercial jets fly. I believe the test was done at 250kts, which is a speed you'll often...
  10. (*steve*)

    Lab Volt Model 790A will not power up

    Picking polypropylene is really just a short cut, I know they are good high voltage capacitors with values in the range you require. You could do the same without picking that first. Axial simply means one lead comes out of each end. This is the style you're replacing. You could leave this...
  11. (*steve*)

    Lab Volt Model 790A will not power up

    It looks like I have you a reference to a Digi-Key part where I was meaning to link to the mouser capacitor. So, let me reach you to fish! (Some of this may vary on a desktop vs mobile view) Go to the mouser site Search for "polypropylene capacitor" Click on the link for "capacitors" (showing...
  12. (*steve*)

    Lab Volt Model 790A will not power up

    I'll have to do that tomorrow. It's just me and my phone at the moment and these sites are a pain on a mobile platform. I would be looking for something with a 2kV rating because I like to have plenty of margin.
  13. (*steve*)

    Lab Volt Model 790A will not power up

    I doubt they are zener diodes. The reverse voltage reading may be due to something else in the circuit. I would lift one end and check them again.
  14. (*steve*)

    My brand new oscilloscope

    Installed! (I'm a blonde, but it's ok. I always have a headset on playing "breathe in... breathe out...") I have a couple of bulbs to replace, then I'll double check everything I've done and power it up!!
  15. (*steve*)

    My brand new oscilloscope

    Ok, so clear heatshrinking kinda makes it less necessary to mark the anode end.
  16. (*steve*)

    My brand new oscilloscope

    And here are the replacements for the selenium rectifiers. I will be heatshrinking thrm, but they don't look so interesting after that :-)
  17. (*steve*)

    WiFi Antenna Composition

    I can still see your posting history. Click on your name/image and the information is there.
  18. (*steve*)

    Amateur (Ham) Radio and RC (Radio Controlled) Flight

    If you employ gain in your transmit antenna you need to be sure you are pointing the antenna at the drone. Something with 26dbi gain will have a beam width of only 7 degrees. This is possibly a little extreme, but you're going to have to be pointing pretty closely. If you're not, it can be...
  19. (*steve*)

    Lab Volt Model 790A will not power up

    It looks to me that the dead resistor is between a high voltage rectifier and the 0.1uF 1000V capacitor. There are a couple of reasons why those three components could be involved in the resistor getting hot enough to die: Failed diode(s) - This will cause AC to alternately charge and...
  20. (*steve*)

    Reflow Bga chip.

    Ah, now I see what you're asking. There are heaters for the bottom of boards. They blow hot air over the bottom of the board to pre-heat the board. The temperature of this air is below the melting point of solder. The idea is to reduce the temperature differential across the board. This...
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