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  1. Audioguru

    555 timer

    A 555 timer does not have an input. But it does have a power supply which can be 12V and it has a trigger input that will begin the timing. Its output with no load will go only to 1.3V less than its supply voltage and the voltage drop changes with temperature and with loading. The 555 draws a...
  2. Audioguru

    Rc car: rf tx to rx

    You cannot control the speed of a motor speed controller (ESC) by feeding binary numbers to it. An ESC uses a variable width (PWM) 50Hz pulse from 1ms to 2ms. The variable width pulses can also be used to control the position of an RC servo. The inputs to the HT12E are supposed to be binary...
  3. Audioguru

    Touch activated torch - increase sensitivity

    There are probably Mosfets available with zener diodes between the gate and source or you can add the zener diodes yourself.
  4. Audioguru

    Rc car: rf tx to rx

    The HT12E and HT12D arte not used to control a radio controlled car. instead they send an address and some data to open a garage door or in a burglar alarm system.
  5. Audioguru

    My first post and help with a project

    The original 2V solar panel controls the LED turning on or turning off. With your new circuit then it will not happen unless you fiddle with a voltage divider from the 14V solar panel. I do not knows what the output of the buck converter will do when the original circuit tries to "charge" it.
  6. Audioguru

    Touch activated torch - increase sensitivity

    Opamps with Jfet or Mosfet inputs are also damaged by static electricity.
  7. Audioguru

    circuit to show how much treble or bass

    I have many blinking and colors-changing LEDs all over my home and my yard. I have a sound level indicator in my family room but it is not a spectrum analyser. My experience and understanding of electronics make the magic for it to happen.
  8. Audioguru

    DAC controlled voltage regulator

    Isn't a laser an LED that has its brightness controlled by its current, not by its voltage? 10mA= fairly dim. 20mA= brighter. 50mA= very bright. 3.0V= fairly dim. 3.1V= brighter. 3.2V= very bright.
  9. Audioguru

    Touch activated torch - increase sensitivity

    Did you look at the datasheet of the tiny battery? It is designed for a load current of only 0.19mA but can supply 6.8mA pulses for a duration of 2 seconds a few times per day, for a few days. You are lucky that your LED uses only a few volts, the Mosfet is more sensitive than most, the tiny...
  10. Audioguru

    Touch activated torch - increase sensitivity

    Some white LEDs need 3.5V to be bright. Not from a 3V battery cell. Some Mosfets need 10V to fully turn on but your Mosfet has no part number. If you try that circuit in winter when the air has low humidity then static electricity will destroy the Mosfet that has no protection.
  11. Audioguru

    My first post and help with a project

    The original circuit is completely different to what you want: It uses a 2V solar panel and a 1.2V battery cell. When there is no voltage from the solar panel (in the dark) it switches off the charging and switches on the LED. When there is voltage from the solar panel then it switches off the...
  12. Audioguru

    Li-ion charging question.

    They might hold a charge with no load for a long time but the capacity will be reduced since they were discharged too low. The capacity (mAh) is how long it can produce a rated current. If the capacity of a Li-ion cell is 3.4mAh then when fully charged (charged at 4.2V until the charging current...
  13. Audioguru

    My first post and help with a project

    One original battery is 1.2V at 1800mAh so if it lasts for 6 hours then its current is 1800/6= 300mA. Its power is 1.2V x 300mA= 0.36W and eight of them total 0.36W x 8= 2.88W. Why did you select a solar panel that is 50W (17 times too big and too expensive)? A solar panel for trickle-charging a...
  14. Audioguru

    Li-ion charging question.

    It is dangerous to charge a lithium battery cell that has been discharged to a voltage less than 3V. It might catch on fire or explode because instead of having lithium ions some of the ions have turned into the metal lithium that shorts the battery and burns like magnesium ) used in flares). A...
  15. Audioguru

    "Variable Voltage Battery charger"

    Your circuit has no voltage regulation and has no current regulation. It has nothing to detect that a battery is fully charged and has nothing to shut off the charging when the battery is fully charged so that it does not become over-charged and boil away its fluids, catch on fire or explode. A...
  16. Audioguru

    Looking for a specific transformer

    A battery charger uses the correct transformer voltage, not a buck converter to reduce a voltage that is too high.
  17. Audioguru

    Looking for a specific transformer

    Hundreds of transformer voltages are available. A common transformer that is 12VAC produces rectified and filtered 15VDC. One hundred years ago a light dimmer (potentiometer) for a theater stage was huge, weighed a few hundred pounds and cost a fortune. Today we use electronics in a battery...
  18. Audioguru

    Alternative Transistors for LM317 High Current Voltage Regulator Circuit

    The problem is worse when the output voltage is close to the input voltage because then the 470 ohm base resistor has a small voltage across it and a low current in it. The datasheet of an LM317 shows LM195 output transistors that have extremely high current gain. The datasheet does not show a...
  19. Audioguru

    Headset music volume dimmer

    Signals into headsets are AC, not DC. A transistor works with DC, not AC so it will cause severe distortion. Stereo is not + and -. Both channels must be mixed together with resistors then the resistor outputs connected together make mono.
  20. Audioguru

    Looking for a specific transformer

    30VAC? A battery is charged with DC, not AC. A fullwave bridge rectifier makes DC pulses with a peak voltage of (30VAC x 1.414V) - 2V for the diodes= 40.4VDC which is much too high to charge a 12V battery that is normally charged with 14VDC. Since the peak voltage is much higher than 30VAC then...
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