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  1. audioguru2

    Infrared Activated Switch

    Then for your continuous modulation, the receiver's gain is reduced by its AGC. They don't say how much the gain is reduced so you will have to try it to see. ;D
  2. audioguru2

    Infrared Activated Switch

    Hi Hamoodyjamal, It's too bad you blew-up your IR receiver. The TSOP1756 and TSOP1156 are almost the same, the TSOP1156 has a slightly quicker data rate. I noticed that they reduce their sensitivity during continuous IR at 56kHz, since their max number of 56kHz cycles is 70. Your system will...
  3. audioguru2

    Fet driving question

    Kevin, The gate of a Mosfet doesn't have any connection to the drain or source, and it doesn't draw a gate current because it is the plate of a capacitor. A power Mosfet consists of thousands of little Mosfet cells in parallel, so their tiny input capacitance adds up to about 2nF. In order for...
  4. audioguru2

    MOSFET AMPLIFIER

    Hi Shaiq, Instead of having a microphone preamp with plenty of voltage gain that is matched to the microphone, driving an efficient power amplifier also with voltage gain to drive a speaker, you have sketched a circuit without much voltage gain, that will draw a massive current from the supply...
  5. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Ta, The original project used 4.7k for R4 and a 5.6V zener diode without a part number for D8. Therefore the current in both was only 1.2mA. If you used a 1W 1N4734 5.6V zener diode that is made to operate at 45mA, then it probably won't regulate and have a voltage in the original circuit of...
  6. audioguru2

    Fet driving question

    Thanks Bjorn, Fairchild recommends only 4.7 ohms? Wow, my driver's output impedance is usually much more than that. Their very high switching frequency benefits efficiency with such a low series resistance. ;D
  7. audioguru2

    LED nite light schematic

    You will probably find the triac blown. They use cheap triacs to meet the cheap product's price, and for small size. An incandescent lightbulb draws 10 times more current when cool than its very high temperature operating current, and a very high current when the filiament burns out or breaks...
  8. audioguru2

    Fet driving question

    I have seen 100 ohms in series with the gate of power Mosfets to keep them from oscillating at a very high frequency when switching. If the value is too high, the Mosfet switches slowly because the resistor limits current that is needed to charge the high gate-source capacitance. ;D
  9. audioguru2

    Fet driving question

    The resistor to the gate of a Mosfet stops the Mosfet from making very high frequency oscillation when it switches.
  10. audioguru2

    tan-timers wanted to buy

    I don't recommend using only a 3V battery for the Redciruits Tan Timer. Its ordinary Cmos ICs have an absolute minimum supply voltage of 3V, and a 3V battery drops to 2V over its life. Red had trouble with his Plants Watering Watcher circuit where only a certain brand of ICs worked at 3V, but it...
  11. audioguru2

    transformer

    Hi Cody, You don't need a regulator for a dumb IR LED but maybe if you are modulating it. If you modulate it then it will be cooler and you can use a cheap high gain very reliable 3-pins IR receiver module for better range and less interference. I just measured my 6VDC/500mA wall-wart. It is...
  12. audioguru2

    Convert 0-30V 3A PSU to 5A or more

    Hi Kain, With a quick look, your schematic is fine. Your U1 stage is sick, its output should be 11.2V. Check that the values of R5 and R6 are equal. The gain of U2 and the output stage is (56k/27k) + 1 = 3.074. Your 9.08V X 3.074 = 27.9V. U2 will have a little more gain by itself because it...
  13. audioguru2

    Convert 0-30V 3A PSU to 5A or more

    Hi Kain, Where is your voltage being lost? 1) D8 is 5.6V. R5 and R6 are equal so the output at pin6 of U1 should be 11.2V. 2) U2 has a high input impedance so there shouldn't be much loss to its input pin3. 3) U2 has 56k for R12 and 27k for R11 so it and the outputs gain should be 3.074. 4) The...
  14. audioguru2

    Ok, only one more question about transistors, I promise!!

    Hi f4, 1) Start with the LED, D1. You don't want to blow it out, so you don't want to operate it at its absolute maximum current. Choose 20mA. 2) Calculate R3. When the transistor is turned on, it will have about 0.2V from its collector to its emitter. The LED has 1.6V across it and therefore...
  15. audioguru2

    high voltage photo flash capacitor charger

    Yeah sure! Charge those 50 capacitors to 340V and put them all in series. Wow! The resulting 17,500V at a high discharge current is bound to do some nasty damage. ;D
  16. audioguru2

    Infrared phototransistor

    With a very bright light up close, the phototransistor conducts only about 10mA. A transistor can amplify the 10mA to about 800mA. If you want a range of maybe 10m, then the phototransistor will conduct only a few uA and additional amplification of its output can be done with an opamp. ;D
  17. audioguru2

    transistors

    A transistor has a range of DC current gain. It is different between two transistors with the same part number and is different at different collector currents. The transistor's datasheet explains it all. By looking at the labelled picure of it on its datasheet. Only the input circuit to your...
  18. audioguru2

    Infrared phototransistor

    Hi f4, Your problem is shown on the phototransistor's datasheet. It is a low current light sensor, not a high current motor driver. With a very bright light it conducts only 10mA. It is shown to saturate fairly well when it conducts only 0.1mA. Your motor might draw 100mA or more. You need to...
  19. audioguru2

    Infrared Activated Switch

    Hi Chow Chow, ;D I thought you want the 555 to be triggered when the IR beam is blocked. The IR receiver's output is low when there is IR radiation, and goes high when the IR is blocked. That is why I added an inverting transistor to its output, so that it can trigger (low) the 555. That is what...
  20. audioguru2

    solder

    I can get just about anything in Canada, and I was talking to Cody who can also get just about anything in the US. I am sorry, Gsmaster, that you or others live in a country with limitations. :(
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