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Nick Gray

 

Nicholas Gray

Nicholas has worked in the Semiconductor industry for over 30 years and has authored a number of published articles about data converters (ADCs and DACs) and signal integrity issues.

 

  • in reply to Former Member
    I am sorry, but I am not sure just what kind of "help" you need because the part types are indicated on the schematic. U1 is a "7805" type linear regulator, U2 is a "MAX232", J2 is what is known as a "DB9" connector which is used for RS-232RS-232 interfaces and J1 appears to be a header to connect to whatever is sending and receiving data over the RS-232RS-232 port.

    The 7805 comes in TO-3, TO-220, TO-263 and SOT-223 packages. I believe that any of these packages would be satisfactory, but the SOT-223 and TO-263 packages MIGHT not handle the power requirements of this circuit (max 105mW) without care in how it is mounted. See the data sheet for proper mounting considerations. The TO-220 package should have no problems with power dissipation. Furthermore, I would prefer the LM340 because its specification shows a a little tighter tolerance on the output voltage. Data sheet is at http://www.national.com/ds/LM/LM340.pdf.

    The MAX232 was first introduced by Maxim Integrated Products, but is now available from other semiconductor manufacturers and is available in 16-pin plastic DOP and SOIC. C2 and C3 are used for the on-chip voltage multiplier to boost the +5V from the 7805 or LM340 to +12V and -12V. Data sheet is at http://datasheets.maxim-ic.com/en/ds/MAX220-MAX249.pdf.

    If none of this answers your questions, please clarify just what you need and I will try to provide your answers.
  • in reply to Former Member
    I am sorry, but I am not sure just what kind of "help" you need because the part types are indicated on the schematic. U1 is a "7805" type linear regulator, U2 is a "MAX232", J2 is what is known as a "DB9" connector which is used for RS-232RS-232 interfaces and J1 appears to be a header to connect to whatever is sending and receiving data over the RS-232RS-232 port.

    The 7805 comes in TO-3, TO-220, TO-263 and SOT-223 packages. I believe that any of these packages would be satisfactory, but the SOT-223 and TO-263 packages MIGHT not handle the power requirements of this circuit (max 105mW) without care in how it is mounted. See the data sheet for proper mounting considerations. The TO-220 package should have no problems with power dissipation. Furthermore, I would prefer the LM340 because its specification shows a a little tighter tolerance on the output voltage. Data sheet is at http://www.national.com/ds/LM/LM340.pdf.

    The MAX232 was first introduced by Maxim Integrated Products, but is now available from other semiconductor manufacturers and is available in 16-pin plastic DOP and SOIC. C2 and C3 are used for the on-chip voltage multiplier to boost the +5V from the 7805 or LM340 to +12V and -12V. Data sheet is at http://datasheets.maxim-ic.com/en/ds/MAX220-MAX249.pdf.

    If none of this answers your questions, please clarify just what you need and I will try to provide your answers.
  • in reply to Former Member
    I am sorry, but I am not sure just what kind of "help" you need because the part types are indicated on the schematic. U1 is a "7805" type linear regulator, U2 is a "MAX232", J2 is what is known as a "DB9" connector which is used for RS-232RS-232 interfaces and J1 appears to be a header to connect to whatever is sending and receiving data over the RS-232RS-232 port.

    The 7805 comes in TO-3, TO-220, TO-263 and SOT-223 packages. I believe that any of these packages would be satisfactory, but the SOT-223 and TO-263 packages MIGHT not handle the power requirements of this circuit (max 105mW) without care in how it is mounted. See the data sheet for proper mounting considerations. The TO-220 package should have no problems with power dissipation. Furthermore, I would prefer the LM340 because its specification shows a a little tighter tolerance on the output voltage. Data sheet is at http://www.national.com/ds/LM/LM340.pdf.

    The MAX232 was first introduced by Maxim Integrated Products, but is now available from other semiconductor manufacturers and is available in 16-pin plastic DOP and SOIC. C2 and C3 are used for the on-chip voltage multiplier to boost the +5V from the 7805 or LM340 to +12V and -12V. Data sheet is at http://datasheets.maxim-ic.com/en/ds/MAX220-MAX249.pdf.

    If none of this answers your questions, please clarify just what you need and I will try to provide your answers.
  • in reply to Former Member
    I am sorry, but I am not sure just what kind of "help" you need because the part types are indicated on the schematic. U1 is a "7805" type linear regulator, U2 is a "MAX232", J2 is what is known as a "DB9" connector which is used for RS-232RS-232 interfaces and J1 appears to be a header to connect to whatever is sending and receiving data over the RS-232RS-232 port.

    The 7805 comes in TO-3, TO-220, TO-263 and SOT-223 packages. I believe that any of these packages would be satisfactory, but the SOT-223 and TO-263 packages MIGHT not handle the power requirements of this circuit (max 105mW) without care in how it is mounted. See the data sheet for proper mounting considerations. The TO-220 package should have no problems with power dissipation. Furthermore, I would prefer the LM340 because its specification shows a a little tighter tolerance on the output voltage. Data sheet is at http://www.national.com/ds/LM/LM340.pdf.

    The MAX232 was first introduced by Maxim Integrated Products, but is now available from other semiconductor manufacturers and is available in 16-pin plastic DOP and SOIC. C2 and C3 are used for the on-chip voltage multiplier to boost the +5V from the 7805 or LM340 to +12V and -12V. Data sheet is at http://datasheets.maxim-ic.com/en/ds/MAX220-MAX249.pdf.

    If none of this answers your questions, please clarify just what you need and I will try to provide your answers.
  • in reply to Former Member
    I am sorry, but I am not sure just what kind of "help" you need because the part types are indicated on the schematic. U1 is a "7805" type linear regulator, U2 is a "MAX232", J2 is what is known as a "DB9" connector which is used for RS-232RS-232 interfaces and J1 appears to be a header to connect to whatever is sending and receiving data over the RS-232RS-232 port.

    The 7805 comes in TO-3, TO-220, TO-263 and SOT-223 packages. I believe that any of these packages would be satisfactory, but the SOT-223 and TO-263 packages MIGHT not handle the power requirements of this circuit (max 105mW) without care in how it is mounted. See the data sheet for proper mounting considerations. The TO-220 package should have no problems with power dissipation. Furthermore, I would prefer the LM340 because its specification shows a a little tighter tolerance on the output voltage. Data sheet is at http://www.national.com/ds/LM/LM340.pdf.
  • in reply to Former Member
    Ken Boyce has given an excellent response. However, I would not use an associative or content addressable memory because they are more expensive than necessary for your application. I believe that an EEPROM is the best solution. For the sake of small size, I would use a serial output ADC and an EEPROM with a serial interface. The output from the ADC is the address of the EEPROM and the data at that address would be the new data to be used. This essentially converts each ADC output word to a new word. Your task is to determine what the relationship between the ADC output and the desired word.

    I am not really into audio, but from what little I know of hearing problems it seems to me that most people suffering from loss have that loss at certain frequencies or range of frequencies. This being the case, I would think that the best solution would be to amplify some frequencies more than others. This would have to be different for each individual, so a tunable filter would be needed that would be adjusted by the doctor or Audiologist for a given individual. My understanding is that such devices are already available, but I am not positive of this.
  • in reply to nickgray
    Hi Nick:  I want to thank you and Ken Boyce for sharing your expertise with me.  I am what might be called an ancient engineer.  It seems that in my educational background I have always been two steps behind the latest technology.   Would you specify the name of an A to D converter and associated serial EPROM that you have suggested that I use.  I will then try to learn enough programming to program according to my own idea for a better hearing aid.  I am looking at the problem from the standpoint of modulation, not frequency. Any other advise would be much appreciated.   Nate Almond
  • in reply to Former Member

    Hi Nate,

     

    One ADC you could look at is the AD9057   ( http://www.analog.com/static/imported-files/data_sheets/AD9057.pdf  ).   Figure 7 shows the evaluation board schematic.  The ENCODE signal would be the clock rate at which you want to convert the analog data.   For voice data, 8KHz sample rate is routinely used, but maybe you want higher resolution, and you could use 16KHz.  The 74ACQ574SJ74ACQ574SJ acts as a temporary data latch between encode cycles.  The output data is 8 bit parallel which could be used as the address to an EPROM such as the AT28C64B from Atmel.  Although it has a 13 bit address (A0 thru A12), you would ignore A8 thru A12 (set to zero).  What ever previously written data you have stored in the EPROM representing the HOH data would be output on its data lines D0 thru D7.

     

    I offer this NOT as a system design, nor a product design, but rather a way for you to test out your theory and an easy way to try out alternative HOH data.

     

    Good Luck

    Ken

  • Hello , i may be asking the wrong person, here gos...

    i got this power inverter ( richmond RI3000 / 12vdc to  110vac )

    i can not get a syn (ciruit digram) the seller on ebay says the manufactor went bank rupted. sorry for my spelling.

    i need some way to get the ciruit prints..

    iam just changing the control chips nte 987 /987sm Quad ,low power OP Amp.

    and nte 1729 Integrated circuit Pulse Width Modulator (PWM) control circuit.

    reasion ... i some way conected the grid power 100 plus amps to the inverters 27 amp out put and i can not see a thing wrong, but when i push the power switch on both leds lite up and there is a sound (like a low battery alarm) .. other then having to remove a few parts to replace at a time

    and keep running to the supply place to get them. can you help or point me in the right direction ?, thanks ed.

     

    a note here please.... you can not have both circuits engaged at the same time. this is not a gridtie inverter

    modifided swine wave power inverter 12vdc to 120vac, 3000 to 6000 watt out put (3000). thanks.