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A Stretch

Discussion in 'General Electronics Discussion' started by SparkyCal, Jun 23, 2020.

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  1. bertus

    bertus Moderator

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    Nov 8, 2019
    hevans1944 likes this.
  2. SparkyCal

    SparkyCal

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    Mar 11, 2020
    Thank-you. I went to the electronics store and bought the film capacitors, along with the op amp that was suggested on this thread.

    I got home and realized that i did not get the 100pF capacitor (C31), which sucks becayuse the electronics store in a 20 minute drive. So.....I took Bertus's advice and ordered https://www.amazon.ca/100V-Polyeste...384011&rps=1&sprefix=film+capa,aps,223&sr=8-5. It is to be delivered tomorrow.
     
  3. SparkyCal

    SparkyCal

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    Mar 11, 2020
    I received the film capacitor kit today. I have a question with respect to the part of the schematic represented in the attached pic, in whihc I have a box around the area, and an arrow poiting to it.

    My question is this:


    You will note that components C31, D2, D1 and the 500K pot, all connect up to the Inverting Input pin (Pin2) of the op amp and the Output pin of the Op amp (Pin 6)

    I am working on a PCB board. To try to keep things tidy, I put two connecttor pins representing Pins 2 and Pin 6, on the board. My question is this:

    Is it important that D2, be connected to C31 and then C31 be connected to the connecting posts I described, or can D2 and C31 be directly run to the posts?

    In other words, is it important to comnect them sequentially to each other (one after another), or, given that all these components are running to Pins 2 and 6, can they all be made to run to the connecting pins directly without connecting to one another first?


    Thank-you
     

    Attached Files:

  4. SparkyCal

    SparkyCal

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    Mar 11, 2020
    I bought these two kits by the way (Thanks Bertus for the recommendation)
     

    Attached Files:

  5. bertus

    bertus Moderator

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    Nov 8, 2019
    Hello,

    Did you see the connnection picture on the page I gave you before?

    Sparkycal_Tone3.jpeg

    Bertus
     
  6. SparkyCal

    SparkyCal

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    Mar 11, 2020
    Yes I did, but I still can't tell if it is important to connect them in a certain order. My sense is that it is not becayse they are not in series, but I don't know
     
  7. bertus

    bertus Moderator

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    Nov 8, 2019
    Hello,

    The order of the capacitor and diodes and the potentiometer is not important.
    As you say, they are all in parallel.

    In the picture you can also see that two pins of the potmeter are connected together.

    Bertus
     
  8. SparkyCal

    SparkyCal

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    Mar 11, 2020
    Thankyou Bertus. I'm sorry to be a pain but I want t make sure I am checking my assumptions. Yes, i beleive the ground connection (left of the pot) amd the middle connector on the pot, are join together. yes?

    ohh..maybe it's the other way? the middle is connected to the right one. I'm second guessing myself now.
     
  9. bertus

    bertus Moderator

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    Nov 8, 2019
    Hello,

    When you connect the middle to the right loop, the gain will go higher when you turn right:

    Sparky_pot.jpg

    Bertus
     
  10. SparkyCal

    SparkyCal

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    Mar 11, 2020
    Thank-you Bertus!!!!
     
  11. SparkyCal

    SparkyCal

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    Mar 11, 2020
    I have attached and circled an area that I have a question on:

    I looked at the graphic above that Bertus posted and here is my interpretation of the circled area on the attached pic.

    With respect to the 10K tone pot, I am thinking it is connected inn the following way:

    The left pin of the 10K tone pot goes to the Negative (-) out of Capacitor C3. (note- in his original schematic, it has been pointed out that he has the polarities incorrectly shown for C3. The negative (-) should be to the right of C3 capacitor. Presently, he has the right marked as +)

    The centre pin of the 10K tone pot goes to ground

    The right pin of the the 10K tone pot, goes to the right pin of the 100K volume pot? I am thinking that is so, because I read that the left pin of a pot is always ground. Correct?

    Actually if someone can explain what pins connect to what pins, between the 10K tone pot and the 100K volume pot, I would greatly appreciate it. I know there is a graphic and schematic, but I am not sure i have interpreted them correctly.

    Thanks so much. Your time and expertise is appreciated and i am learning a lot along the way from you folks!
     

    Attached Files:

    • ss2.jpg
      ss2.jpg
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  12. bertus

    bertus Moderator

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    Nov 8, 2019
    Hello,

    The centerpin goes to the capacitor, the other side of the capacitor goes to ground.

    Bertus
     
  13. SparkyCal

    SparkyCal

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    Mar 11, 2020
    Well guys, I am somewhat disheartened.

    I bought all the right parts and soldered all the components together on a PCB board. It does not work. Here is what i suspect.

    I got really confused when connecting the three potentiometers. I am almost certain that i don't have the 3 poins on each potentiometer connected in the right way. I think i got the pin connections mixed up.

    When I turn the circuit on, there i a lot of noise and no guitar sound coming into the amp. When I rotate each potentiometer, it just turns to degree of noise up or down.

    I am wondering if I can ask a favour. Can someone tell me, like I'm stupid, how to connect up the three pots.

    As in, filling in the following blanks:

    Gain Pot. 500K

    Left Pin goes to____________
    Center pin goes to __________
    Right pin goes to __________

    Tone pot (10k)

    Left Pin goes to____________
    Center pin goes to __________
    Right pin goes to __________

    Volume Pot (100K)

    Left Pin goes to____________
    Center pin goes to __________
    Right pin goes to __________

    I hope this is not too much to ask. I am almost burnt out over this circuit, and can use the help. Every other component, I went to great lengths to connect properly, but the three pots causesd me a lot of confusion and I am sure I screwed their connections up.

    Thank-you
     
  14. duke37

    duke37

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    767
    Jan 9, 2011
    Make sure the centre pin goes to the correct place. If the other two connections are the wrong way round. then the kob will operate in the wrong direction. Just swap them over.
     
  15. SparkyCal

    SparkyCal

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    6
    Mar 11, 2020
    Thank-you. I looked at my pot connections this morning, and I think they are all wrong. I will rewire them when I collect my patience ;-).
     
  16. bertus

    bertus Moderator

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    Nov 8, 2019
  17. SparkyCal

    SparkyCal

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    Mar 11, 2020
    Thank-you. I tried debugging but could not make it work. I am thinking of starting over with a new PCB board. I will read that article before I do. I hope using the single op amp as opposed to the dual did not impact the circuit?
     
  18. SparkyCal

    SparkyCal

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    6
    Mar 11, 2020
    I wonder if I purchased the wrong kind of potentiometer for the 500K one. It has three terminals, as normal, but it also has 2 terminals at the very bottom of it.

    The packaging says POT LIN SW 1/4 IN RND 2 5MM
     
  19. bertus

    bertus Moderator

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    Nov 8, 2019
    Hello,

    The pins on the bottom of the potmeter are for a on/off switch.
    You will likely hear a click when you turn it fully left.
    You do not need them at the moment.
    Just use the three loops on the side of the potmeter.

    What opamp do you want to use?
    In post #6 I posted a datasheet and pinouts.

    Bertus
     
  20. SparkyCal

    SparkyCal

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    6
    Mar 11, 2020
    Thanks Bertus

    On page 2 of this thread AudioGuru wrote the following:

    The TL082 dual opamp should not be used, a TL081 single opamp is all you need and if you use a socket for it then you can easily replace the opamp with a different one.

    I purchased the TL081 single opamp as recommended and downloaded its data sheet to follow the pins. I really don't think the opamp is the issue.

    My next move is tp use my microscope and closely examine each component and connection I made. Also, if folks do not mind, i will post how exactly i have the pots wired.
     
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