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  1. R

    Peak detector to A/D of PIC

    Hi Bob, I am investigating this at the moment. I removed all the A/D code initially, thinking thst this was an easier test. I think by defaiult the PIC A/D is an input I/O pin. But i was still not seeing the signal at the pin. I am going to look at the A/D code again by just puttjng a stable...
  2. R

    Peak detector to A/D of PIC

    Hi thanks for your reply. I am measuring the signal using a oscilliscope. I did consider an opamp voltage follower but do not have enough PCB space to fit it hence trying to use discrete components. How can i over come this issue. Shall try and tweak the RC values? See i need to measure the...
  3. R

    Peak detector to A/D of PIC

    Hi The peak voltage of the pulse is 7V. I have also deleted the A/D code. On normal power up the A/D pin is an input. However, I am still not seeing any signal. If i disconnect the output frim the A/D pin i can see the signal. Could this be a loading issue?
  4. R

    Peak detector to A/D of PIC

    Hi all I have a peak detector circuit below. However when i connect this to the A/D pin of the PIC i get a flat line ie 0V Could this be an impedance matching issue? I have aldo noticed the same thing happen if i attach a low pass RC filter to the PIC A/D ie 100K and 220nF I have thought about...
  5. R

    Volts per metre

    Sorry i wasnt thinking :)
  6. R

    Volts per metre

    Sorry i wasnt thinking :)
  7. R

    Volts per metre

    Yes this us what i want. Trying to relate this to something equivalent. Please could you shiw me how you came across the 1.5m long 1.5V battery. Thanks
  8. R

    Volts per metre

    Ok but what wiuld the field strength of 1V/m be equivalent to? Thats what i am really asking.
  9. R

    Volts per metre

    Thanks for the reply. But how can i equate this to simpler terms for non engineers. What is 1V/m equivalent too? What is the field intensity equivalent too.
  10. R

    Volts per metre

    Hi all, I have a question regarding volts per metre or v/m. I know that this is a unit to measure electric field strength/intensity. I believe thst when we say 1V/m it means at a distance of 1 metre a voltage of 1V strength is applied. I also know it is used in EMC immunity tests. My question...
  11. R

    Square wave to DC level

    Hi all, I have connected the circuit shown below to the PIC A/D. However instead of seeing a square wave coming in , I get a flat line i.e. 0V 1. Could this be due to impedance of the A/D. 2. If the A/D is not set up correctly (I think it defaults as an input on the PIC) would that cause what I...
  12. R

    Square wave to DC level

    Hi all I have connected the peak detector circuit (see pdf above) to the PIC A/D. I monitored the A/D pin but i am not seeing anything. If i disconnect from the PIC i can see the waveform (1.35V pulse signal). Any ideas why this shoukd be the case.
  13. R

    Square wave to DC level

    Sorry i thought i was posting in the same topic.
  14. R

    Square wave to DC level

    Hi As promised I have attached my schematic and simulation. The simulation is exactly what I am seeing. This gives me a voltage of about 1.45V roughly, which I intend to use to the input of the PIC A/D. My question was 1. Do I need a voltage follower or will this setup be ok as I have a 220nF...
  15. R

    Square wave to DC level

    Hi Thanks for your help. I forgot to mention thst i only have one pin of the pic available which is the A/D. I could as you say detect a high and then a low. However would i not need a edge trigger such as capture compare or similar? I will look into this.
  16. R

    Square wave to DC level

    yes i will post a schematic for you.
  17. R

    Square wave to DC level

    Hi all I have a peak detector. This is used to detect 7V pulses of 4KHz equal duty cycle. I have used a voltage divider to reduce this to around 2V. Then the ouput of the voltage divider is fed to s BAT85 diode, which then connects to a 220nF and 43KHz resistor. The other end of the resistor...
  18. R

    Square wave to DC level

    Here are pdfs of my simulations for peak detector circuits Any help would be greatly appreciated
  19. R

    Square wave to DC level

    Hi all, I have an additional complication with the circuit. The 7V pulse signal is when everything is working correctly. However if I get a fault with the circuit, this drips down to a 2V signal (4KHz frequency equal mark to space ratio). I just wanted to ask if the above circuit by Harald would...
  20. R

    Good PCB layout design practices

    Hi all I am learning some schematic capture and layout with Eagle PCB. I eanted to ask whst is generally good PCB design practice. Is it some of the following: 1. Segregate Analogue and Digital circuitry 2. Decoupling caps on all ICs 3. 4 layer stack up woukd be signal gnd power signal 4. Have a...
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