Electronics > Metrology

Marco Reps circuit LT7805 ultra low noise : what is the circuit & caps values

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Maxoverdrive:
Hello
In the very interesting video on YouTube


Marco Reps have built a circuit base on LT7805 with electrolytic cap and ceramic caps to reach amazing low noise result ( for a LT7805 ) and even more compare to costly DC/DC IC

Question : Does that possible to have the schematic of this circuit with BOM

Thanks in advance
MOD

iMo:
In that video that is a standard 7805 voltage regulator, typical values for ceramics are 100nF and he uses electrolytics like 1000uF.
There is also LTC7805 - it is a switcher (not in that video)..

MiDi:
I do not recommend building that circuit.
The OPs that are responsible for low noise are ADA4523.
I rather recommend building Andreas type of low frequency LNA.
See lengthy thread DIY low frequency noise meter

guymo:
More details of this circuit are available on Marco Reps's github:
https://github.com/marcoreps/low_noise_amplifier

Maxoverdrive:
Thanks for your answer
For the L7805 the purpose was to be able to compare with Marco design ( same circuit + same compoenets = same noise ou close )

For the noise amplifier the Marco files on Github are in process so I prefer to work on a stable version rather to launch PCB and order components to generate troubles
the article  on Analog is detailled
https://www.analog.com/en/technical-articles/775-nanovolt-noise-measurement-for-a-low-noise-voltage-reference.html

In both design , the use of precision capacitor is mandatory

Marco Reps works are impressive as his reverse engineering on Fluke Voltage zener reference

If some one on this forum have a link on a validated / finished circuit for noise measurement I will happy to built it

Regards
MoD

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