is cellphone charger 5volts noisy?
noisier than wallmart 9volts?
im going to use it in transistor preamp
noisier than wallmart 9volts?
im going to use it in transistor preamp
Some are very noisy; others, not so much. The worst ones I tested had almost 50 millivolts of high-frequency noise on their outputs, depending on load current. The best ones I had on hand (the "little white cube" chargers for iPhone) had only a couple of millivolts of noise. I don't know what Walmart 9V supplies are like regarding noise, but all the modern "wall wart" supplies I've tested are very noisy.is cellphone charger 5volts noisy?
noisier than wallmart 9volts?
im going to use it in transistor preamp
It might be. I should think two such stages, with 100 ohms and 100 nF and 100 μF in each stage, would almost certainly be enough.do you think 100ohm series and 100nf and 100uf in power supply is enough?
I've never had any luck doing that. First, the noise has always been too low in amplitude to get meaningful readings from my DMM; and second, the noise waveforms are rich in high-frequency harmonics and the DMM doesn't measure such waveforms very accurately.is there a way to measure noise using DMM?
The quality of the power supply has to be better and better as the signal you intend to amplify is weaker and weaker (higher and higher gain needed).do you think 100ohm series and 100nf and 100uf in power supply is enough?
is there a way to measure noise using DMM?
can you give an example of that ihave lots of bc557 bc337Also, the power supply rejection ratio of your preamp and amplifier design. Example, using current mirrors on each side of the long-tailed pair will greatly reduce power supply noise.
is desktop switch mode? if the noise is still unacceptable, im gonna use 9v tranformer chinaI avoid the modern switch-mode power supplies and go for the older (heavy, real iron) transformer based ones.
i dont know, im going to build simple transistor with 30+gain preamp for dynamic micHow much current does your amp draw? 100Ω in series may drop too many volts.
by Jake Hertz
by Duane Benson
by Duane Benson
by Jake Hertz