Search results

Search Forums New Posts
  1. Audioguru

    Need help, regarding LED circuit

    The ebay photo shows about 15 of them for 0.99 of a British pound. Shipping is 3 pounds.
  2. Audioguru

    Finding a nano amp transistor for Solar LED Light Marker

    A transistor or "joule thief circuit" will not work until its supply voltage is at least 0.65V. The output current from a joule thief circuit is very low. If you use two solettes (what is a solette?) in series to produce 1.1V then when the input of a voltage boosting circuit is 20mA its output...
  3. Audioguru

    Finding a nano amp transistor for Solar LED Light Marker

    What is going to charge your 3V battery? Not the 0.5V solette. You made a typo, in dark conditions does the solette produce 0.003mA (3μA) or 3nA? The 9mV is not nearly enough to switch on a transistor that needs about 67 times more. I think you want more than 9mV to turn on the first transistor...
  4. Audioguru

    AC Adapter Help

    If you use a US wall wart then you do not need the voltage converter. Buy a US wall wart that is 24VAC/7.2VA or 300mA or more with the same output connector as the Euro one. Notice that the hole in the connector comes in two sizes so get the same one. Connect the foot switch to the output of the...
  5. Audioguru

    Adding an LED display to an FM radio kit?

    Where can anybody buy that Chinese frequency counter IC that is made for radios? Digikey and Newark know nothing about it.
  6. Audioguru

    Need help, regarding LED circuit

    The ad for the cheap Chinese no-name-brand LEDs is missing the important spec's of brightness and viewing angle. They might be too dim and might produce such a narrow beam that you cannot see them unless they shine directly at you. They might be fine in a flashlight but poor for a bicycle. From...
  7. Audioguru

    Short distange battery operated(door bell type) alarm

    He wants 4 of them to have accurate fairly close distances detected.
  8. Audioguru

    Short distange battery operated(door bell type) alarm

    The size of the sensed object affects the sensitivity of an IR motion detector or ultrasonic distance detector very much. The result will show the distance plus or minus the size. IR does not work in daylight and ultrasonic does not work where there are noise sounds.
  9. Audioguru

    Piezo-charger

    They placed thousands of piezos on a sidewalk and rectified their output then charged a battery. After thousands of people walked on the piezos then the battery charge lighted a little LED for an hour. I think many rectified piezos can power a modern low current watch.
  10. Audioguru

    5mm LED Voltage Help Needed

    Of course the mA stays the same as a single LED when they are in a series circuit, they all use the same current. Your LEDs "might be" 1.3V but they are spec'd to be from 1.2V to 1.4V. Then your 110 ohm resistor, 3 LEDs in series and a 5V supply produces a current from 7.3mA to 12.7mA and will...
  11. Audioguru

    Chinese Hiland 0-30V/Audioguru PSU build (down the rabbit hole)

    The inputs of U3 are pin 3 which is a voltage given by the current setting pot P2 and pin 2 which is a voltage from the project's output current sensing resistor R7. Since there is no load then pin 2 voltage should be almost zero and pin 3 voltage should be a little positive that causes the...
  12. Audioguru

    5mm LED Voltage Help Needed

    The IR LEDs are very cheap therefore they have poor quality. The spec's say nothing about current but an answer to a question says 10mA (not 100mA) and at 10mA then 10% of them will burn out soon. For 3 LEDs in series then the resistor is (5V - 3.6V)/30mA= 46.7 ohms. If the LEDs are 1.4V then...
  13. Audioguru

    Finding a nano amp transistor for Solar LED Light Marker

    I have many cheap Chinese solar garden lights. The old ones used solar panels and light dependant resistors that got sunburned, and old Ni-Cad battery cells that failed or rusted away in a couple of months. Newer ones use a solar panel with a glass cover that does not sunburn and it detects the...
  14. Audioguru

    Adding an LED display to an FM radio kit?

    I learned how to solder so many years ago that I can't remember what I did next to learn about electronics. I think I learned the basics of electronics in school and from magazines then learned the details in university.
  15. Audioguru

    Chinese Hiland 0-30V/Audioguru PSU build (down the rabbit hole)

    Your BC547 is made by a Chinese company so maybe their Engrish is too bad for them to say on their sketch "bottom view" or maybe it is a S9015 relabeled to show BC547. Who cares about Q3? All it does is turn the LED on and off and it has nothing to do with the DC voltage at pin 2 of U3 being...
  16. Audioguru

    Homemade light-bar (LED query)

    The solar lights produce only 160 lumens amount of light that is about 1/1000th what you want. The 25W incandescent light bulb in your refrigerator or a 7W LED produces more light.
  17. Audioguru

    Chinese Hiland 0-30V/Audioguru PSU build (down the rabbit hole)

    I looked in Google for BC557 and this is the first datasheet (it is from ON Semi) I found:
  18. Audioguru

    Heating coils with a 9v, why doesn't this work?

    Why not look up "how to make a VAPE thingy".
  19. Audioguru

    Bone conduction low frequency speaker

    A properly damped speaker starts and stops immediately. A vibrator motor starts and stops slowly due to its inertia.
  20. Audioguru

    Bone conduction low frequency speaker

    Sure, but its loudness will be reduced a lot (because then it must work harder) and to make it loud enough it might burn out.
Top