Can You Help Me Achieve a 5x DC Gain for Opamp Output Voltage?

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Discussion Overview

The discussion revolves around achieving a 5x DC gain for an op-amp output voltage, specifically targeting a solution that can output +/- 150v without resorting to expensive high voltage op-amps. Participants explore various circuit designs and components, including opto-isolators and voltage dividers, while addressing the specific requirements of the application involving a tube amplifier's grid biasing.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant seeks a workaround for achieving a 5x DC gain for an op-amp output voltage to bias a tube amplifier's grid.
  • Another participant requests additional specifications regarding the type of signal (DC) and current draw (inherently 0 due to high impedance).
  • Suggestions include using an opto-isolator to control power from a high voltage supply, with caution regarding design and safety considerations.
  • Concerns are raised about the speed of opto-isolators, with participants debating what constitutes "slow" in this context.
  • Discussion includes the potential for using a DC-DC converter to achieve the required voltage, with some participants expressing uncertainty about the feasibility of multiplying voltage versus just offsetting it.
  • Clarifications are made regarding the function of voltage dividers in determining gain and the necessity of a high voltage supply for achieving high output voltages.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the best approach to achieve the desired voltage gain, and the discussion remains unresolved with no consensus on a single solution.

Contextual Notes

Limitations include the need for specific circuit designs to handle both positive and negative voltages, as well as the requirement for a high voltage supply to achieve the desired output. Some participants note the complexity of the circuit and the potential for misunderstanding its purpose.

  • #31
A time constant of around 1hz would work. Thanks jim you're a hero :) Now onto the next issue.
 
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  • #32
coinmaster said:
By DC offset servo I mean an opamp integrator that I use to bias a triode to maintain a DC null at the output of the stage. As in the non inverting input is attached to ground and the inverting input is attached to the output of the stage and I adjust a trimmer so the opamp outputs a proper bias voltage to maintain a DC null at the output of the stage based on its input.

A question well stated is halfway answered.

Bravo - that was very clear !

thanks, and good luck !
old jim
 
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