creating virtual ground - Page 1
Forum section: electronics / projects

author: justin66
author_rank: Regular Contributor
timestamp: July 28, 2015, 03:26:16 pm
content: hey guys i have build an amplifier that require split lane PSU and i only have single lane so i looked up suggested resistor devider method by a member kleinstein and i found this circuit. the thing is the specified values didnt work so i increased c1 and c2 to 2200uf and decreased r1 and r2 to 2.5 Kohm the amplifier lm3886t works but when i crank up the volume i hear weird clicking noise and if i put a lot of bass it just doesn't play it turns off and clicks every second. what should i do to prevent this?my setup is: 100VA transformer rated at 17V AC 5.88A and i get 23.7V DC with a bridge rectifier and two 10000uf and 4700uf caps what should i change to get rid of that clicking sound when i play music with bass or straight 30hz sinewave?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 28, 2015, 03:28:50 pm
content: Change the amp (so it's not sensitive to its apparent ground voltage being pushed around all the time), or increase the capacitors so much that you never see the effect within the bandwidth of the amplifier (undesirable for other reasons), or get a proper split supply transformer.Tim

author: justin66
author_rank: Regular Contributor
timestamp: July 28, 2015, 03:32:05 pm
content: could it be that there is not enough voltage?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 28, 2015, 03:46:26 pm
content: That sounds like the problem, yes. But:When you play a loud, deep bass note, it discharges the capacitors to one side. Hence, less voltage (between one supply and "GND").The purpose of the split capacitors is so that this discharge happens alternately, during a bass note. But it sounds like you're playing it too loud, or too low, for the amount of capacitance you have. So it's browning out and shutting off. Or something.Hmm, LM3886 is also rated for 20V minimum supply. Yeah, you really should be using something other than that, or a higher voltage. It can handle some +/-40V, so, you aren't very limited on what transformers you can use.Tim

author: justin66
author_rank: Regular Contributor
timestamp: July 28, 2015, 03:51:55 pm
content: ok i have added 10miliFarads cap and it helped like this: when amp wasnt playing at all adding 10mF cap made it play with that weird ticking sound and when i connected it to v- and v+ it didnt help either but with that charge connected to v- and gnd speakers amplitude decreased and that weird sound gone for a few seconds and as time gone amplitude was getting bigger and sound come back. how should i interpret this? should i increase voltage? or what ? coz tda2050 amp is not as good on 12v as on 23v

author: justin66
author_rank: Regular Contributor
timestamp: July 28, 2015, 03:55:23 pm
content: Quote from: T3sl4co1l on July 28, 2015, 03:46:26 pmthanks ! i will look into getting a beefy split lane transformer

author: Zero999
author_rank: Super Contributor
timestamp: July 29, 2015, 08:08:12 am
content: Why make so many damned threads for the same project?It's possible to configure the LM3886 so it works on a sinlge 24V power supply, so my response to the other thread.https://www.eevblog.com/forum/projects/what-a-hell-is-this/msg719051/#msg719051