Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Recent content by Alistair Ballantyne

  1. A

    4017 decade counter failure

    Hi – this was the last piece of the jigsaw which resulted in success!! I changed the 0.47uf cap for a 1.0uf electrolytic cap and it worked as it should. Bit disappointed that a circuit from a beginner’s book is so flawed – wrong resistors, wrong placement and wrong capacitor. All added to the...
  2. A

    4017 decade counter failure

    Hi - I've put the 47k into the pot input as you suggest and used the 330R in series with the negative rail of the 10 LED's I've changed the pot, the 555 and the 4017. Unfortunately doesn't make any difference - when connected all 10 LED's illuminate but do not "chase". Adjusting the pot makes no...
  3. A

    4017 decade counter failure

    Hi – I can’t get this circuit to work and don’t see why. The circuit calls for a 47k resistor from negative terminal to the connection of LED’s but I get nothing to work at all with this arrangement. If I take out the resistor then: If the pot is turned up then all LED’s remain lit (no...
  4. A

    speaker size for LM386

    Hi Brian, Stupidly I see this has answered one of my later questions so thanks! One other if I may: A simple LM386 mono amp (schematic below) driving an MP3 player through a basic 8 ohm / 1.5W speaker. How long would you expect a 9V battery to last powering this? I made a box to use as...
  5. A

    speaker size for LM386

    Hi Dana, Thanks. Would not have thought of that so very interesting and useful. Still not totally clear though. Is that the data sheet for the LM386? So at 9V it has a max output of 0.5W? What would be the effect of using a, say, 5W 8ohm speaker? Regards, Alistair
  6. A

    speaker size for LM386

    Hi, Simple LM386 amp with 8 ohm speaker. What would be your max wattage recommendation for the speaker? Thank you. Alistair
  7. A

    Help with simple op amp circuit

    Thanks for that. Any chance you could let me have the circuit details for your LM390 amp? Regards, Alistair
  8. A

    Help with simple op amp circuit

    Thanks Dana - good material to investigate. The 1000uf option I understand gives superior smoothing, filtering and stability. Certainly performs better than the usually prescribed lower uf options. Regards, Alistair 1614948372 Thanks for that useful insight. Therefore the bridged circuit...
  9. A

    Help with simple op amp circuit

    Thanks Dana - a lot of useful information. I did make the bridged circuit which you kindly forwarded. It worked for a while from an MP3 player but for some reason just stopped. As two LM386’s are used I thought it would provide a little more power to the speaker than the original circuit I...
  10. A

    Help with simple op amp circuit

    Thanks Klaus, Yes I am about to wire up Dana's bridged circuit. It will be interesting to compare with I have done so far. On your second point - can you please give me any pointers to find a "more modern circuit"? Many thanks, Alistair
  11. A

    Help with simple op amp circuit

    Thanks Dana - sorry I don't yet have a scope. Is this what's called a closed loop circuit to more accurately control the gain of the amplifier? In your view should this circuit work? I don't want to spend any more time trying to rewire if it is suspect in your opinion. Many thanks Alistair
  12. A

    Help with simple op amp circuit

    Hello, I made a simple LM 386 mono amplifier circuit with an MP3 player and 8 ohm speaker. It worked well. To create a stereo amplifier I simply made two identical mono circuits and fed right and left jack plug inputs from the MP3 into each circuit, with a common ground. I was surprised at...
  13. A

    Beginners confusion... (water detect transistor circuit)

    You’re right Dana – the absence of R2 doesn’t seem to make any difference at all! I’m a bit disappointed because this circuit is from the ‘Electronics for Dummies’ book and so thought would be very robust as a simple circuit for beginners. Judging from the comments from experienced members...
  14. A

    Beginners confusion... (water detect transistor circuit)

    That explains things well Brian, thank you. The book ‘Electronics for Dummies’ outlines basic principles well but doesn’t explain included circuits (like this one) in any detail. Any advice on the best source of simple circuits with detailed explanation of whats happening in the circuit? Thanks.
  15. A

    Beginners confusion... (water detect transistor circuit)

    Very useful and informative Brian, thank you. The value of R2 is only 10k but it still works ok. I am struggling with the basics here. I calculate the current as 0.6A. (9V vcc -2V LED drop – 0.7 Vbe) / 10470 = 0.6A. Turning that round the other way to get the voltage across the base as V =...
See more

Part and Inventory Search

Back
Top