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Only the CMOS chips MC14538 and the op-amps use the -5V rail. But is it really necessary?
The CMOS logic level "1" must be 0V to open the JFETs. However, the CMOS "0" can be as low as -30V (reverse Vgs rating of J113), so why not use -VB instead of -5V? The NE555 would interface directly with the CMOS without the need of R4.
The op-amps need a +5V rail because the input is referenced to 0V. However, since the preamp is inverting we want as much negative headway for the output as we can get. This would make negative saturation more difficult (faster recovery from the transient) and increase the dynamic range. So why not use -VB here as well?
Less components, less saturation, larger dynamic range... replacing -5V by -VB seems to have only advantages.
The CMOS logic level "1" must be 0V to open the JFETs. However, the CMOS "0" can be as low as -30V (reverse Vgs rating of J113), so why not use -VB instead of -5V? The NE555 would interface directly with the CMOS without the need of R4.
The op-amps need a +5V rail because the input is referenced to 0V. However, since the preamp is inverting we want as much negative headway for the output as we can get. This would make negative saturation more difficult (faster recovery from the transient) and increase the dynamic range. So why not use -VB here as well?
Less components, less saturation, larger dynamic range... replacing -5V by -VB seems to have only advantages.
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