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  1. alfa88

    Negative voltage: practical application

    In my opinion plus should be connected to plus and negative to negative. Do not connect either negative or positive to ground. The purpose of ground is to literally carry current to ground should voltage accidentally, somehow touch the case. I don't see a problem with either laptop...
  2. alfa88

    Can anyone identify these capacitors?

    That red mark looks like a polarizing indication. Do you think they might be electrolytics and perhaps a much higher value. Example: 331=330uF.
  3. alfa88

    Who is this manufacturer? Data sheet?

    Mostek, Thomson, Hughes? But my vote goes for Thomson http://www.datasheetarchive.com/integrated-circuit-logos/
  4. alfa88

    Additional pass through transistor or bigger reg?

    Take a look at my project log. I just posted it a couple of days ago. It uses 2- lm338s. As long as the 2 secondaries are not connected to each other; who needs a negative regulator? I might have gone a little overboard on the heatsinks but that's what I had laying around .
  5. alfa88

    How does a satellite transmit data?

    Achh! I mis spoke again! SHD:rolleyes:
  6. alfa88

    How does a satellite transmit data?

    I think what you're asking is how transmitters and receivers work. Resonance. Imagine you were in a piano store with a friend. You sit at one piano and he at another across the room. Your friend strikes a key. If the pianos are properly tuned your piano's string will vibrate at the same...
  7. alfa88

    New Power Supply

    The MJE3055s are on the inside of the rear heatsink, the NTE184s are heatsinked on a pc board. I heatsinked the bridges as well. I'll add that 1k resistor. Thanks for the suggestion. Not bad for just hand tools hand drill and a Dremel, eh?
  8. alfa88

    New Power Supply

    The new supply is just about finished. I waiting on a couple panel meters, a couple caps and new regulators. In addition I have to tweak some resistors in the current limiting section. The transformer has enough headway where if I want a couple more Amps I can add a little more circuitry. The...
  9. alfa88

    asking for a help

    I will suggest finding a test equipment kit. Be it a multimeter, power supply or signal generator. You will most likely be able to find one that's pre-built cheaper but the knowledge and documentation you get from a kit can be invaluable. Back in the day us old timers had Heathkit, Knightkit...
  10. alfa88

    light to power

    Solar cells are pretty much the same stuff as transistors but in a larger scale. This guy had a lot of spare transistors and time to prove a point: http://hackaday.com/2012/04/13/using-diodes-and-transistors-as-solar-cells/#more-71533
  11. alfa88

    Need help downgrading amp to lower power

    The advantage a LM317 has is that you can adjust the voltage. So if I'm figuring out Duke's calcs right you could adjust the Voltage to 8.4V and you're done.
  12. alfa88

    Need help downgrading amp to lower power

    Duke's solution is exactly what I was thinking. A LM317 regulator will work nicely.
  13. alfa88

    My Power Supply Saga

    Are you referring to R1? In all cases I'm using a 150Ohm from Output to Adjust. I corrected my simplified drawing to reflect...
  14. alfa88

    My Power Supply Saga

    Uh?! The bad part was a LM338K(TO-3), the good part was a LM338T(TO220). The application is the same. I like the heat dissipation of the TO-3 and besides, my heat sink is drilled for a TO-3.. The seller refunded me so I'll shop around again.
  15. alfa88

    My Power Supply Saga

    Well I finally broke the 4Amp barrier. and no it wasn't a miswire. I had opted for the TO-3 package and went bargain hunting on EBay. It seems that I got a bad batch. 4 baddies in a row. Fortunately I bought some TO-220 types at the same time. They're not giving me the full 5A but at least now I...
  16. alfa88

    My Power Supply Saga

    No Load: In - 24-25Vdc Out - 22.4 to 1.5Vdc 10 Ohm load: In - 21.7-23.6Vdc Out - [email protected] to [email protected] 5 Ohm load: In - 21.4-23Vdc Out - [email protected] to [email protected] 3 Ohm load: In - 21.6-23Vdc Out - [email protected] to [email protected]
  17. alfa88

    My Power Supply Saga

    I have a string of 10 resistors for a total of 10 Ohms. 3 Ohms is as low as I go.
  18. alfa88

    My Power Supply Saga

    Am I unclear on a concept or what? I'm trying to put together an adjustable 1-15V power supply. I tried a lm317 with a Voltage follower. Didn't work out so I'm going with a LM338. The most I can get out of it is 2A. I made sure the bottleneck wasn't the transformer to bridge section by loading...
  19. alfa88

    Solar Panel Control Circuit

    What you speak of is a charge controller. If one were to overcharge or over discharge a battery that lessens the life of a battery. A charge controller has set limits as to these levels. In addition deep cycle batteries are used that are more tolerant to the discharge / charge cycles. A quick...
  20. alfa88

    blowing up capacitors

    As soon as I get my new PS built I got some 'sperimentin' to do.:eek:
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