Thanks for quick reply.
I agree that voltage doubling chip makes voltage chokes that defeat the whole idea of stabilized power supply. Did you forget that my LED needs 3.9v and LM317 has 3v drop so I need at least 7volts for my USB port.
Another problem with changing the circuit is that I have mesured about 150 samples using it and even with digital multimeter I doubt it's possible to match resistors I have now so.
It could be possible with multimeter with 4 digit 3.000volts etc. but those are very expensive. The cheap ones as you know have 10% or 15% accuracy range - so having 3 digits like 3.00volts has no sense as it would mean that there can be 0.3volt precision lag.
I read that there is MAX 660 and MAX 665 chips:
MAX 660
Converts voltage from +1.5 to +5.5 V to −1.5 to −5.5 V without any chokes, only two capacitors are required. Can also be used as a voltage-doubler. The MAX 660 is a pin-compatible upgrade of ICL 7660
MAX 665
Converts voltages from +1.5 to +8 V to −1.5 to −8 V without any chokes, only two capacitors are required. Can also double the voltage.
Perhaps these would work?
I agree that voltage doubling chip makes voltage chokes that defeat the whole idea of stabilized power supply. Did you forget that my LED needs 3.9v and LM317 has 3v drop so I need at least 7volts for my USB port.
Another problem with changing the circuit is that I have mesured about 150 samples using it and even with digital multimeter I doubt it's possible to match resistors I have now so.
It could be possible with multimeter with 4 digit 3.000volts etc. but those are very expensive. The cheap ones as you know have 10% or 15% accuracy range - so having 3 digits like 3.00volts has no sense as it would mean that there can be 0.3volt precision lag.
I read that there is MAX 660 and MAX 665 chips:
MAX 660
Converts voltage from +1.5 to +5.5 V to −1.5 to −5.5 V without any chokes, only two capacitors are required. Can also be used as a voltage-doubler. The MAX 660 is a pin-compatible upgrade of ICL 7660
MAX 665
Converts voltages from +1.5 to +8 V to −1.5 to −8 V without any chokes, only two capacitors are required. Can also double the voltage.
Perhaps these would work?