Search results

Search Forums New Posts
  1. duke37

    Help with 19 LED VU Meter circuit (LM3915/16)

    A resistor to drop the voltage is not a good idea since the drop will depend on the current through it which will depend on the number of leds which are lit. You could use a power supply with a lower voltage or put a zener diode in the line to drop a specific voltage, make sure the zener can...
  2. duke37

    LED and 555 timer help

    Rectification from the mains will not reduce the chance of death. If you cannot find a safe low voltage supply, then you should not do it. As an alternative to a plugpack, you could use a USB supply or an old style battery charger if you want a lot of current. You have been bitten once...
  3. duke37

    Simple wiring problem

    Transformers will give a lower voltage when loaded, this is called regulation. A good transformer may drop 5% at full load current. Small, cheap transformers may drop 20% at full load. There are even some transformers which can stand a short on the output without burning out. Measure the...
  4. duke37

    Simple wiring problem

    It is not clear what the voltage at the transformer is, it is 11.8V with no current. The transformer will have a lot of wire in it and the terminal voltage will drop with increased load current.
  5. duke37

    LM555 oscillator

    A approximation to a sine wave could be achieved by using a few stages of attenuation each stage using a series resistor and a parallel capacitor. The effect would change if the frequency changes.
  6. duke37

    Simple wiring problem

    I have an old table of wire resistances. 16 awg = 18 swg 13.3 ohms/1000yd 14 awg = 16 swg 7.6 ohms/1000yd 12 awg = 14 swg 4.8 ohms /1000yd Remember that the current has to go there and back.
  7. duke37

    hello from shropshire

    Welcome to Electronics Point. I come from a farming background in Shropshire so you are in good company ! I joined Electronics Point to discuss a faulty electric fencer, there is much good advice here.
  8. duke37

    help with circuit PLEASE!

    You do not say what the circuit should do or the chip which you have used so pin numbers are unclear. With a permissible power supply of 3V to 16V perhaps it is a CMOS 4093. I assume the circuit is a bistable. The circuit diagram is clear enough to easily read but your english should not...
  9. duke37

    Transistor assisted ignition circuit

    I think the reason for two zeners in series is to get enough voltage. The TIP162 has a maximum collector voltage of 400V. two 150V in series will limit the collector voltage to 300V. Two 150V zeners may be easier to find than one 300V zener. By connecting the zeners back to the base of the...
  10. duke37

    Electric motor power increase question

    So the computer could know that the motor is stalled and could reduce the current to a safe level. A short burst now and then could be generated to see if the motor would be able to overcome the resistance.
  11. duke37

    Electric motor power increase question

    "Yep, I know that. But these FFB wheel makers have been doing it for the last 10+ years " How do they achieve the force feedback?
  12. duke37

    Electric motor power increase question

    You are likely to burn out a DC motor if you stall it and put a large current through. The armature windings will not share the current and the commutator will get heated assymetricaly. Normally a motor takes a lage current to start but the heat is distributed as the motor rotates, then as...
  13. duke37

    An interesting(to me anyways) project

    I would suggest that you get a few leds of different types and look to see if they suit. Look at brightness and viewing angle. Do not overrun the led, they will need a series resistance which depends on the particular led and the drive voltage. Viewing angles can be as low as 10 degrees...
  14. duke37

    Making two first circuits

    The relay contacts will need to have a specification exceeding 12V and exceeding the current that the pump draws.
  15. duke37

    An interesting(to me anyways) project

    A CMOS 4017 Johnson counter will count with a single output from 0 to 9. It can be made to reset part way through the sequence. Each LED will need its own transistor driver but they may be in the strip you get. We will need the specification of the LEDs that you intend to use.
  16. duke37

    Automated Sliding Door

    You cannot put a diode across the motor if it is turning in both directions, you could use a couple of zener diodes back to back. Have you thought of a scrap electric car window?
  17. duke37

    What Is The Ohm Of This Resistor

    The typical energy in the pulse is 1J, within a factor of ten ! Taking 1J at 1/sec gives 1W so the power required is very low and a surge resistor for the input circuit would dissipate very little power. Putting the yellow loop through half the core would presumably give a lower output than...
  18. duke37

    An interesting(to me anyways) project

    A CMOS 4093 (my favorite) can make two oscillators and two invertors. The 4093 can drive FETs (need sensitive gate to run on 6V) which can switch several amps. Some thought would be needed to put in simple switching unless two separate systems are used, one for left and the other for right.
  19. duke37

    What is this 5 pin part? Factory car stereo.

    The part could be a stereo power amplifier for driving the speakers. It should have a type number on it.
  20. duke37

    What Is The Ohm Of This Resistor

    The big capacitor has 250V marked on it. Assuming 1J in the pilse, the supply current can be estimated if the capacity is known. The blown resistor may be in the input line to get this capacitor charged (to 200V)) in 1 second. The LM324 is a quad op amp. A first check would be to see if...
Top