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  1. BobK

    Basic transistor Guitar Amp

    Here is the amp I have been talking about. It is intended to take the output from an MP3 player and so a guitar is a bit lower than than that and it put out just barely audible sound. If you combine it with your original amp it should produce a little bit of sound from a guitar. This amp runs...
  2. BobK

    Basic transistor Guitar Amp

    The power dissapation in the output transistors is not the same as the output power. For a 1 Watt amplifier, in a push pull stage, they would only be dissapting 1/2 Watt each of the efficiency was 50%, which would be way low. So, I still maintain that you would easily get 1W out of a 2N2222 /...
  3. BobK

    amplify ultrasound signal

    First, a tweeter cannot be rated as 4 or 8 Ohms, it is one or the other. Which is it? To put 200W into an 8 Ohm speaker requires 40V RMS with is a whopping 112V p-p at about 1.8A. For a 4 Ohm speaker it is 28V RMS or 78V p-p at about 2.5 Amps. You can find integrated circuit amps that...
  4. BobK

    Voltage regulating.

    A linear regulator acts like a variable resistor, it changes its resistance to make its output at the regulated voltage independent of the current being drawn. For any linear regulator all of the difference in voltage is wasted as heat in the variable resistor. So given an input voltage Vin...
  5. BobK

    James Bond CIA Gadget Challenge

    You could prove it on yourself, but it at that point, winning won't make much difference to you. I don't see any reason why it is impossible. If the skin is breached, it takes very little voltage and current to kill. Bob
  6. BobK

    Self-holding transistor (or anything else) needed!!!

    http://www.ecelab.com/circuit-transistor-scr.htm Bob
  7. BobK

    infrared LED

    Well, I saw Elvis yesterday at the convenience store, and he was wearing highly reflective pants. Bob
  8. BobK

    Basic transistor Guitar Amp

    As I stated above, it would be good for up to about 1 Watt output. Bob
  9. BobK

    Basic transistor Guitar Amp

    You could, but you would not want to. If you are using those transistors a darlington is not needed. The darlington configuration is needed with more high power transistors which have lower gain. After work, I can post a circuit using 2n3904 and 2n3906 that I have built, but its output is...
  10. BobK

    measuring AC ripple on 5 volt PS

    Oh, Okay. My digital scope does this as well, IF i remember to set it correctly. I was thinking of my analog scope, which does not, Bob
  11. BobK

    Basic transistor Guitar Amp

    The output stage will depend on how much power you want to produce. If you are looking at <1W something like 2n2222 / 2n2907 pair would work fine. For more power you will be looking for power darlington compilmetary pairs. Bob
  12. BobK

    Voltage regulating.

    Well, the description calls it buck converter, why would think it is not?
  13. BobK

    measuring AC ripple on 5 volt PS

    Did you multiply the reading by 10 when you used the 10X probe? I.e. if you are using a 10x probe and you read 1V the actual reading is 10V. Bob
  14. BobK

    Need some resistance help

    Do not listen to the above advice, you do not charge a 12V battery to 7V. You don't even discharge a 12V battery to 7V normally. Bob
  15. BobK

    Basic transistor Guitar Amp

    That amplifier will produce a gain of 10, not nearly enough to take the input from a guitar to drive a speaker. You would need a gain of about 100 to hear anything and 1000 to make it reasonably loud. A reasonable low-power discrete transistor amp, would have two gain stages, like the one...
  16. BobK

    Basic Capacitor Question

    1. Yes, the capacitor can be removed from the charging circuit and attached to another circuit in which is it discharged. 2. The discharge rate depends on what it is connect to. If you short circuit the leads, it will discharge very quickly. If you put 1MoHM resistance between the leads...
  17. BobK

    IC socket orientation - I made a boo boo!

    If you are talking about DIL sockets, yes, you can plug the IC in correctly even if the socket is backwards, all the pins simply go straight through. On the other hand, it might be a good time to learn de-soldering techniquies. You need a desoldering tool which vacuums off the solder after...
  18. BobK

    1.5 KW power supply

    I think most people here would not be comfortable giving advice on a project that dangerous. Bob
  19. BobK

    first pcb stebs - sallen key filter

    Post images if you want us to look at it. Bob
  20. BobK

    Help circuit for project idea.

    Okay, makes more sense now. Bob
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