Search results

  1. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Ruden, If you give the circuit an input voltage too low, the resistors won't supply enough current unless their value is reduced. Also the parts for the negative DC voltage will need adjustment. If the input voltage is too high then the currents will be too high and cause resistors and...
  2. audioguru2

    Camping Music Box - PROJECT

    Hi Stuee, It is difficult to make a battery status indicator. The battery will be from 13.8V to 14.4V (if it is lead-acid) when it is fully charged. Then it quickly drops to about 12.6V for most of its discharge. Near the end of its charge its voltage quickly drops more and more.The indicator...
  3. audioguru2

    PC speakers amp with TEA2025

    Hi Autir, Only a few cm of unshielded wire will pickup hum from the mains since your amp circuit has a lot of gain. Your amp's output cables to the speakers don't need shielding but the wiring from the pots to the IC must be shielded or inside a metal box connected to the circuit's ground. Wires...
  4. audioguru2

    PC speakers amp with TEA2025

    Hi Autir, Your good news is very good. You did a fine job making a stereo amplifier. ;D The hum in your bad news should be easy to fix. 1) Use shielded audio cables to the inputs of your amp, not a headphones extension cord. 2) Your amplifier probably doesn't hum when nothing is connected to...
  5. audioguru2

    Transmitting Power??

    All traffic lights in my city have a little sensor with a "baseball cap" on it, shielding it from the sun, I guess. It probably detects the flashing strobe lights on emergency vehicles. I am waiting to see what will happen if two emergency vehicles arrive at an intersection at right angles at...
  6. audioguru2

    trafic signal

    I think that the sun emits IR, therefore how would they make an IR detector that isn't sensitive to IR? ??? ???
  7. audioguru2

    PC speakers amp with TEA2025

    He, he. I didn't know Philips made a contact lens cleaner! ;D ;D It will do your job. If you look on the datasheet for the TEA2025, it shows a DC voltage of a whopping +0.04V on both inputs. Therefore the polarity of the C7 and C8 electrolytic caps are correct. ;D
  8. audioguru2

    PC speakers amp with TEA2025

    Hi Autir, 1uF for C7 and C8 in your circuit might reduce "POP" sound when it is turned on. The value of pots R1 and R2 in your new circuit doesn't affect this amplifier. It is the load on the source that is feeding them. Most sources can drive 10k. Pots are noisy when you adjust them if they...
  9. audioguru2

    ElCheapo PSU

    Even a fast-blow fuse takes a fairly long time to blow so passes 7A pulses for about one milli-second with no problem. A fuse reacts to the average current which is low in your circuit. High-power audio amplifiers have a huge filter capacitor in their power supply. It takes many half-cycles of...
  10. audioguru2

    Camping Music Box - PROJECT

    Hi Ante, My modified clock radio and the radio in my old car had "loudness" controls that passively boosted the bass when they were turned down. As described by the "Fletcher-Munsen" curves of response changes of our hearing at reduced levels. The bass was always at the same level so didn't...
  11. audioguru2

    ElCheapo PSU

    Hi Autir, As you can see by the low ripple voltage at the filter capacitor, the rectifiers conduct to charge it for only a very short period of time for each half-cycle of the mains. But in order to add the same amount of charge during charging that the 0.7A load removed during continuous...
  12. audioguru2

    PC speakers amp with TEA2025

    Hi Autir, Now that R3 and R4 are drawn correctly they appear to be simple volume controls. When the slider is grounded then the amp input gets no signal. The amp had less gain than recommended by ST Micro with its R5 and R6 added, and had R1, R2, R3 and R4 to reduce the gain even more...
  13. audioguru2

    Camping Music Box - PROJECT

    Hi Stuee, Which amp circuit do you have that gives 40W output with only a 12V battery? You should never short together stereo outputs of anything to get mono. The outputs will fight each other and might be damaged. I designed a passive circuit to add the channels with two 10k resistors and...
  14. audioguru2

    need help... urgent!! plzzzzz

    Hi Alun, C2 has a very small value because it is used to correct the frequency response of the opamp IC2A. The 1M negative feedback resistor R4 and the high impedance of the non-conducting photodiode causes a high frequency peaking effect due to stray capacitance at the inverting input of the...
  15. audioguru2

    Camping Music Box - PROJECT

    You said that your solar cell is only 4.5mw? I don't think so. The tiny solar cell on my calculator is rated the same and is the size of my thumbnail. It is probably 4.5W, and will overcharge the battery and dry it out. You need a circuit to stop the charging when the battery is fully charged...
  16. audioguru2

    Sequential Timers with PWM Motor Speed Control

    Hi Ante, My test flights crashed not due to pilot error nor electronic malfunction. It was due to avionics physics. It goes too fast and therefore climbs too steeply. Then stalls and dives into the ground. I have the balance, elevator, rudder and ailerons set so it glides very well. There are...
  17. audioguru2

    Transmitting Power??

    hi Meee, Welcome to our forum. ;D Transmit power and range depend entirely on whether the modulating signal is analog or digital, the RF frequency, AM or FM (or fancy digital types), and wideband or narrowband. Of course it also depends on the sensitivity of the receiver, if there is an...
  18. audioguru2

    Camping Music Box - PROJECT

    Hi Stuee, If you get a clock radio, get a good one (most are crap) and with an LCD display, since an LED display uses a lot of current continuously. ;D
  19. audioguru2

    Coil gun charger circuit

    Hi Mr. Heckles, Your circuit is different from the original. Your Mosfet is very nice. Your driver IC is very nice. But no wonder the Mosfet heats-up, is gate drive voltage is too low! :o Even in the original circuit the gate drive voltage is too low. Your 7808 regulator could have a 7.6V...
  20. audioguru2

    need help... urgent!! plzzzzz

    Hi Awright, Welcome to our forum. ;D At the top of this page is a row of buttons. The one labeled "Projects" links to our projects section. The Park-aid project that Ann Margareth is building can be found there and its link is here...
Top