Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
thanks very much for all the info mosaic. im building the filter. do you think its worth leaving the big cap bank? how would it be possible for it to not interact with the filter? and sry i cant grasp where are the +ve and -ve low volt rails? inside the smps?
+ve & - ve voltage rails are simply the output + and - that you connect to the load. Try it without the big cap bank to avoid the current tripping problem which will require the NTC resistor
what i would do for the current peak is probably connect a 11w resistor in series with the cap bank and short it with a relay 555 timer circuit set on one-shot mode and 1sec or smthing like that, since the ntc would heat up the box. and it should even the peak to some point But looks like im building a filter as ive found 2.6amp 400uh coils and am thinking to use 6 of them in parallel getting 66uh and with 220uf cap the filter would result a cutoff of 1.3khz. could i somehow separate the filter from the big cap bank to still use it, but without changing cutoff. if the bank and filter cap would sum the calc says the cutoff would go down to 80hz and imp vould be 0,03 which sounds not so good??
another thing, isnt this kind of capacitor use(large banks) working as a lowpass filter on their own, since theres some inductance just from the wire?
thx again for the time
Keep it simple my friend. The purpose here is to solve the problem with as few components/expense as possible. Leave off the capacitor bank, I don't believe you need it with the proper LC filter in place.
All capacitors and inductors have some self inductance and capacitance. The same applies to a simple resistor. That resonance (tank circuit) begins to matter at the higher frequencies of operation in the multi MHz range. Thus PCB design, dimensions, trace layout, wave guides, proximity effects and electric skin effect all come into play.
so ive built the 1.3khz lp lc filter and it seems not as noisy, but still not silent enough for recording. ive learned a lot thx for all the support.
ive come to few questions i couldn't find answers to:
1.DO you think by limiting this smps 220va 12v output with a 9v regulator would get rid of the switching noise and could get a clean 9v line for my addac, effect pedals and instruments, while still having my computer on the line?
2.what are good ways to cancel (or separate) the ground(9v audio line from 12v computer line)?
i need around 3amps in total, could i use 3 regulators (like for 3x 1a outputs) from the same 12v line?
3.what are good steps to take, if i manage to get to use an oscilloscope, for identifying and canceling the noise?building an negatively resonant filter for the f of noise?
4.what are the better up to date regulators for audio use(under 40$ range)?
You can take a look at this regulator: https://www.ti.com/lit/ds/symlink/lm350-n.pdf
Build it like Fig. 22.You can probably use the metal case of your 12 volt supply as a heat sink.
You never mentioned recording before.
If you're using the internal sound digitizing of the computer you won't escape the digital noise crosstalk inside the box. Things like hard drive motors and fan electrical noise etc. will create a noise floor in your recording. The PSU isn't the only source of noise.
You'd need an external audio breakout box with balanced line in to effectively use the PC for audio recording with good results.
I have done a fair bit of broadcast TV work using 16 bit , 44.1 or 48 Khz sampled audio. Usually I'd have to do post processing to 'conceal' the hissy noise floor of such recordings. Having very good front end input 'signal to noise' dynamic range permits suppressing a few dB in post and making the noise floor unimportant. An audio compressor can help here. A gate with a ramp envelope can help in the post for the 'silent' parts. Good quality, short , neat signal cables help, Don't run audio cable in the same harness or conduit with power cables.. Also, having a dedicated 120VAC line, 30A 4mm square wiring minimum, with NO other taps on it for your studio is important. You don't want a water pump or refrigerator compressor adding electrical noise during a recording. Avoid CFL and LED lights like the plague...they broadcast serious noise. Switch 'em off before recording.
im having an external interface(no balanced input tho) witch can be powered by 9v, i suppose it cuts off the noisy usb ground and power when using a 9v psu(havent tested, if not ill be using one of those usb isolators) im in a need for clean 9v line with common ground for the audio interface and the instruments, preamps and fx that go in to it(around 3amps) The point is, i am on the crossroads of building a nice separate regulated 9v psu from another transformer or just to regulate(and somehow cancel the noise from) the 12v from the smps. Is there any way to isolate this noisy computer ground just for the regulated 9volts? if id manage to scope the noise would that allow me to filter it easily? any tips with that?
thx for the stuff mosaic, comp and a noise gate is not working for me since its too much that would get clipped off at this point, for now i also cant get a separate line for the studio, but i definitely will in the future
You need a decent low impedance line to true earth. We don't know the condition of the earth in the 120VAC socket....how long or how poor/corroded the connection is to true earth.
First you should establish a good earth connection.
This is what cable TV guys do...they sink their own copper rod for a good earth and not rely on debugging the possibly noisy 'building' ground. Electricians do that as well when rewiring a house...sink a 3' copper coated steel rod.
**broken link removed**
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
Avoid CFL and LED lights like the plague...they broadcast serious noise. Switch 'em off before recording.
