Pre-amplifier input protectionDesigning a 30 watt audio amplifier50 volts regulated power supplyRegulated...

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Pre-amplifier input protection


Designing a 30 watt audio amplifier50 volts regulated power supplyRegulated audio inputAnalog preprocessing circuit (anti-alias/pre-amp) for driving ADCHow are the resistor values R1 and R2 calculated for a transistor amplifier that has a voltage divider biasConnect LED from audio output without it blinking?Some questions regarding input stage of audio signals to the pre-amplifierCrossover distortion returns when load is appliedHow build a practical AC over voltage protection circuit for the input of an arduino boardQ: Need help designing Pre-Amplifier













1












$begingroup$


I am building the Velleman K1803 pre-amplifier kit. This amplifier has a maximum input signal of 40mv. The audio input to the pre-amplifier will be a piezo-electric sensor, and this can certainly exceed the specified maximum.



I believe that the input can be protected with a pair of diodes, but there is a huge range of diodes available.



It is some time since I have done any electronics, and so far my searches have not resulted in a suitable circuit design which could achieve the protection at the low signal voltage specified. For the record, the input is audio in the range 20Hz to 20kHz, and could possibly lie in the range +/- 0.5V.



I would appreciate some guidance on where to look for a suitable diode and circuit. I can of course supply a circuit diagram of the amplifier if needed










share|improve this question







New contributor




Geoff is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$








  • 3




    $begingroup$
    Normally you would clamp to the maximum that the input can take, not the expected maximum of the signal source. It is likely that the 40mV maximum is the maximum that the amp can take and still work properly...but you're not worried about that. You're worried about the maximum it can take and not have damage occur. There's a difference. You can either use a TVS diode that clamp in reverse-breakdown or "regular" sufficiently fast diodes that clamp in forward bias to clamp the voltage to the rail supply (but this requires a rail supply to be present).
    $endgroup$
    – Toor
    3 hours ago


















1












$begingroup$


I am building the Velleman K1803 pre-amplifier kit. This amplifier has a maximum input signal of 40mv. The audio input to the pre-amplifier will be a piezo-electric sensor, and this can certainly exceed the specified maximum.



I believe that the input can be protected with a pair of diodes, but there is a huge range of diodes available.



It is some time since I have done any electronics, and so far my searches have not resulted in a suitable circuit design which could achieve the protection at the low signal voltage specified. For the record, the input is audio in the range 20Hz to 20kHz, and could possibly lie in the range +/- 0.5V.



I would appreciate some guidance on where to look for a suitable diode and circuit. I can of course supply a circuit diagram of the amplifier if needed










share|improve this question







New contributor




Geoff is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$








  • 3




    $begingroup$
    Normally you would clamp to the maximum that the input can take, not the expected maximum of the signal source. It is likely that the 40mV maximum is the maximum that the amp can take and still work properly...but you're not worried about that. You're worried about the maximum it can take and not have damage occur. There's a difference. You can either use a TVS diode that clamp in reverse-breakdown or "regular" sufficiently fast diodes that clamp in forward bias to clamp the voltage to the rail supply (but this requires a rail supply to be present).
    $endgroup$
    – Toor
    3 hours ago
















1












1








1





$begingroup$


I am building the Velleman K1803 pre-amplifier kit. This amplifier has a maximum input signal of 40mv. The audio input to the pre-amplifier will be a piezo-electric sensor, and this can certainly exceed the specified maximum.



I believe that the input can be protected with a pair of diodes, but there is a huge range of diodes available.



It is some time since I have done any electronics, and so far my searches have not resulted in a suitable circuit design which could achieve the protection at the low signal voltage specified. For the record, the input is audio in the range 20Hz to 20kHz, and could possibly lie in the range +/- 0.5V.



I would appreciate some guidance on where to look for a suitable diode and circuit. I can of course supply a circuit diagram of the amplifier if needed










share|improve this question







New contributor




Geoff is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$




I am building the Velleman K1803 pre-amplifier kit. This amplifier has a maximum input signal of 40mv. The audio input to the pre-amplifier will be a piezo-electric sensor, and this can certainly exceed the specified maximum.



I believe that the input can be protected with a pair of diodes, but there is a huge range of diodes available.



It is some time since I have done any electronics, and so far my searches have not resulted in a suitable circuit design which could achieve the protection at the low signal voltage specified. For the record, the input is audio in the range 20Hz to 20kHz, and could possibly lie in the range +/- 0.5V.



I would appreciate some guidance on where to look for a suitable diode and circuit. I can of course supply a circuit diagram of the amplifier if needed







amplifier audio diodes protection






share|improve this question







New contributor




Geoff is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|improve this question







New contributor




Geoff is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









share|improve this question




share|improve this question






New contributor




Geoff is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









asked 3 hours ago









GeoffGeoff

61




61




New contributor




Geoff is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.





New contributor





Geoff is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






Geoff is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.








  • 3




    $begingroup$
    Normally you would clamp to the maximum that the input can take, not the expected maximum of the signal source. It is likely that the 40mV maximum is the maximum that the amp can take and still work properly...but you're not worried about that. You're worried about the maximum it can take and not have damage occur. There's a difference. You can either use a TVS diode that clamp in reverse-breakdown or "regular" sufficiently fast diodes that clamp in forward bias to clamp the voltage to the rail supply (but this requires a rail supply to be present).
    $endgroup$
    – Toor
    3 hours ago
















  • 3




    $begingroup$
    Normally you would clamp to the maximum that the input can take, not the expected maximum of the signal source. It is likely that the 40mV maximum is the maximum that the amp can take and still work properly...but you're not worried about that. You're worried about the maximum it can take and not have damage occur. There's a difference. You can either use a TVS diode that clamp in reverse-breakdown or "regular" sufficiently fast diodes that clamp in forward bias to clamp the voltage to the rail supply (but this requires a rail supply to be present).
    $endgroup$
    – Toor
    3 hours ago










3




3




$begingroup$
Normally you would clamp to the maximum that the input can take, not the expected maximum of the signal source. It is likely that the 40mV maximum is the maximum that the amp can take and still work properly...but you're not worried about that. You're worried about the maximum it can take and not have damage occur. There's a difference. You can either use a TVS diode that clamp in reverse-breakdown or "regular" sufficiently fast diodes that clamp in forward bias to clamp the voltage to the rail supply (but this requires a rail supply to be present).
$endgroup$
– Toor
3 hours ago






$begingroup$
Normally you would clamp to the maximum that the input can take, not the expected maximum of the signal source. It is likely that the 40mV maximum is the maximum that the amp can take and still work properly...but you're not worried about that. You're worried about the maximum it can take and not have damage occur. There's a difference. You can either use a TVS diode that clamp in reverse-breakdown or "regular" sufficiently fast diodes that clamp in forward bias to clamp the voltage to the rail supply (but this requires a rail supply to be present).
$endgroup$
– Toor
3 hours ago












2 Answers
2






active

oldest

votes


















2












$begingroup$

A pair of inexpensive back-to-back silicon diodes across the input lines should be sufficient to limit input to 600 mV. Germanium diodes or Schottky diodes would keep the voltage lower yet, but they're generally more fragile and/or more expensive than ordinary Si iodes. Since the specifications limit response to 20 kHz, even Si rectifier diodes should not degrade performance noticeably.



Though the maximum rated signal for the Velleman K1803 is 40 mV, there is no DC path from input to IC1a, below, so a transient 600 mV should do no harm.



Velleman K1803 schematic from https://www.velleman.eu/downloads/0/illustrated/illustrated_assembly_manual_k1803_rev2.pdf






share|improve this answer









$endgroup$









  • 1




    $begingroup$
    R2 puts a severe limit on transient current into the IC anyways. Not sure the OP has a transient problem to fix. Reducing R5 to reduce gain may be a better choice.
    $endgroup$
    – Sparky256
    1 hour ago



















2












$begingroup$

Just change one of the feedback resistors to have less gain so it can accept larger input voltages without clipping.






share|improve this answer









$endgroup$













    Your Answer





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    2 Answers
    2






    active

    oldest

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    2 Answers
    2






    active

    oldest

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    active

    oldest

    votes






    active

    oldest

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    2












    $begingroup$

    A pair of inexpensive back-to-back silicon diodes across the input lines should be sufficient to limit input to 600 mV. Germanium diodes or Schottky diodes would keep the voltage lower yet, but they're generally more fragile and/or more expensive than ordinary Si iodes. Since the specifications limit response to 20 kHz, even Si rectifier diodes should not degrade performance noticeably.



    Though the maximum rated signal for the Velleman K1803 is 40 mV, there is no DC path from input to IC1a, below, so a transient 600 mV should do no harm.



    Velleman K1803 schematic from https://www.velleman.eu/downloads/0/illustrated/illustrated_assembly_manual_k1803_rev2.pdf






    share|improve this answer









    $endgroup$









    • 1




      $begingroup$
      R2 puts a severe limit on transient current into the IC anyways. Not sure the OP has a transient problem to fix. Reducing R5 to reduce gain may be a better choice.
      $endgroup$
      – Sparky256
      1 hour ago
















    2












    $begingroup$

    A pair of inexpensive back-to-back silicon diodes across the input lines should be sufficient to limit input to 600 mV. Germanium diodes or Schottky diodes would keep the voltage lower yet, but they're generally more fragile and/or more expensive than ordinary Si iodes. Since the specifications limit response to 20 kHz, even Si rectifier diodes should not degrade performance noticeably.



    Though the maximum rated signal for the Velleman K1803 is 40 mV, there is no DC path from input to IC1a, below, so a transient 600 mV should do no harm.



    Velleman K1803 schematic from https://www.velleman.eu/downloads/0/illustrated/illustrated_assembly_manual_k1803_rev2.pdf






    share|improve this answer









    $endgroup$









    • 1




      $begingroup$
      R2 puts a severe limit on transient current into the IC anyways. Not sure the OP has a transient problem to fix. Reducing R5 to reduce gain may be a better choice.
      $endgroup$
      – Sparky256
      1 hour ago














    2












    2








    2





    $begingroup$

    A pair of inexpensive back-to-back silicon diodes across the input lines should be sufficient to limit input to 600 mV. Germanium diodes or Schottky diodes would keep the voltage lower yet, but they're generally more fragile and/or more expensive than ordinary Si iodes. Since the specifications limit response to 20 kHz, even Si rectifier diodes should not degrade performance noticeably.



    Though the maximum rated signal for the Velleman K1803 is 40 mV, there is no DC path from input to IC1a, below, so a transient 600 mV should do no harm.



    Velleman K1803 schematic from https://www.velleman.eu/downloads/0/illustrated/illustrated_assembly_manual_k1803_rev2.pdf






    share|improve this answer









    $endgroup$



    A pair of inexpensive back-to-back silicon diodes across the input lines should be sufficient to limit input to 600 mV. Germanium diodes or Schottky diodes would keep the voltage lower yet, but they're generally more fragile and/or more expensive than ordinary Si iodes. Since the specifications limit response to 20 kHz, even Si rectifier diodes should not degrade performance noticeably.



    Though the maximum rated signal for the Velleman K1803 is 40 mV, there is no DC path from input to IC1a, below, so a transient 600 mV should do no harm.



    Velleman K1803 schematic from https://www.velleman.eu/downloads/0/illustrated/illustrated_assembly_manual_k1803_rev2.pdf







    share|improve this answer












    share|improve this answer



    share|improve this answer










    answered 2 hours ago









    DrMoishe PippikDrMoishe Pippik

    8867




    8867








    • 1




      $begingroup$
      R2 puts a severe limit on transient current into the IC anyways. Not sure the OP has a transient problem to fix. Reducing R5 to reduce gain may be a better choice.
      $endgroup$
      – Sparky256
      1 hour ago














    • 1




      $begingroup$
      R2 puts a severe limit on transient current into the IC anyways. Not sure the OP has a transient problem to fix. Reducing R5 to reduce gain may be a better choice.
      $endgroup$
      – Sparky256
      1 hour ago








    1




    1




    $begingroup$
    R2 puts a severe limit on transient current into the IC anyways. Not sure the OP has a transient problem to fix. Reducing R5 to reduce gain may be a better choice.
    $endgroup$
    – Sparky256
    1 hour ago




    $begingroup$
    R2 puts a severe limit on transient current into the IC anyways. Not sure the OP has a transient problem to fix. Reducing R5 to reduce gain may be a better choice.
    $endgroup$
    – Sparky256
    1 hour ago













    2












    $begingroup$

    Just change one of the feedback resistors to have less gain so it can accept larger input voltages without clipping.






    share|improve this answer









    $endgroup$


















      2












      $begingroup$

      Just change one of the feedback resistors to have less gain so it can accept larger input voltages without clipping.






      share|improve this answer









      $endgroup$
















        2












        2








        2





        $begingroup$

        Just change one of the feedback resistors to have less gain so it can accept larger input voltages without clipping.






        share|improve this answer









        $endgroup$



        Just change one of the feedback resistors to have less gain so it can accept larger input voltages without clipping.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered 1 hour ago









        JustmeJustme

        2,0221413




        2,0221413






















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