The revisions involve switching from a single to bipolar power supply, and increasing the capacitance of two capacitors of the circuit. See the attached schematics of the original and revised designs.
To take the noise outputs of the circuit with respect to common of the bipolar supply, I reversed the polarity of electrolytic capacitors C2 and C7 connected to the collector of respectively transistors Q2 and Q3. This was done based on the fact that with the revised circuit I measured DC voltage of the collectors of Q2 and Q3 being several volts negative with respect to the power supply common.
The other revision involves increasing C1 and C3 from 25 uF to 100 uF, just because I don't have 25 uF caps on hand. C3 I believe blocks DC in the connection from the white noise output to low-pass filtering to produce pink noise; this means I think that increased capacitance of C3 is acceptable. The function of C1 in the circuit is unknown to me, so I'm uncertain if making C1 of greater capacitance than given can be done.
Thanks in advance for letting me know if my changes will or will not degrade noise generation of this circuit.
-Pete
To take the noise outputs of the circuit with respect to common of the bipolar supply, I reversed the polarity of electrolytic capacitors C2 and C7 connected to the collector of respectively transistors Q2 and Q3. This was done based on the fact that with the revised circuit I measured DC voltage of the collectors of Q2 and Q3 being several volts negative with respect to the power supply common.
The other revision involves increasing C1 and C3 from 25 uF to 100 uF, just because I don't have 25 uF caps on hand. C3 I believe blocks DC in the connection from the white noise output to low-pass filtering to produce pink noise; this means I think that increased capacitance of C3 is acceptable. The function of C1 in the circuit is unknown to me, so I'm uncertain if making C1 of greater capacitance than given can be done.
Thanks in advance for letting me know if my changes will or will not degrade noise generation of this circuit.
-Pete