my 1st ever D-amp, WORKING!!!

[kartino]

Hi raff,

just post your last schematic.

 

[RX5]

Hello Kartino,

Its STILL the same schematic.. only with "tweaked" value.... now im currently adding op-amp input... im using NE5532...

Cheers
Raff

 

[RX5]

Chris,


LM6172 as op-amp buffer perhaps??

 

[Kuzmenko]

It really does not matter, what opamp you would use for it. It`s not THAT case. So, if you already have 5532 - use it!

 

[classd4sure]

I guess it matters!!

BTW opa2134 is also a good candidate, cheap too.

 

[RX5]

all IS ok.... But only 5532 IS locally available in our area 🙂

 

[RX5]

to jan-peter/bruno

just a simple question.. how do you power your op-amp input buffer?

LM317/337 or discrete(transistor/zener/resistor) ??

thanks
-Raff

 

[Kuzmenko]

This is not matter too 😉
The simpler - the better. And be warned about max. input voltage for 7815/LM317/etc.

 

[RX5]

ok... simpler... sener/resistor 🙂

I was quiet wondering WHAT those TO220 where..in the UcD180/400 .... twas next to 22uF/50V bypass caps...

 

[classd4sure]

They're power transistors set up as followers with some added filtering. Don't use the zener without it...

Simpler the better... op amp choice doesn't matter? Some advice.

You can do it pretty simple, research it, also research CRCRC filters.

It all matters, they key is to do it within your ability/cost, and not overcomplicate without worthy benefits. That's good design.

You could also try batteries just for kicks 🙂 Don't forget to make the ground common.

 

[RX5]

You could also try batteries just for kicks Don't forget to make the ground common.

nice one.. i WILL do it...😀 much simpler/better.. i USE rechargable battery and get charging current from supply 😀


got one here now... boosted zener 🙂


now making -board- in cad.... 😉

 

[classd4sure]

Be carefuly making your own charger. Do a little research on recharging the specific batteries you want to use, because they can explode.

Also I'm not sure if there's any benefit to using them if they're connected to the dirty supply during operation.

 

[RX5]

Be carefuly making your own charger. Do a little research on recharging the specific batteries you want to use, because they can explode.

Also I'm not sure if there's any benefit to using them if they're connected to the dirty supply during operation.

jsut kidding

😀

anyway, I have made board... op-amp NE5532 buffer + supply reg for it.... post pic later.... ok I measured supply... +/-14VDC @ 100mA(maybe?).. used 2n5551/5401

measured pin #1 and #7 .. its 10mV DC .. with reference to ground... is THIS ok?? 😉

 

[classd4sure]

It's going to be amplified by whatever your output stage gain is. So, it's adding up. That's why an op2134 might be better, or AC couple at the output of the op amp.

 

[RX5]

10mV power rails you say? Simulate my man.

yow! pin#1 and pin#7 ARE op-amp output (NE5532)... read datasheet 🙂

😀 😀 😀 😀

 

[classd4sure]

That's why I edited it... gimme a break, it's 4 in the morning.

 

[RX5]

That's why I edited it... gimme a break, it's 4 in the morning.

hhhmmm too late a post? hhehehe nah.. no big deal.. 🙂

anyway, NE5532 is -=the best=- I could find in our area... I dunno if the store where I buy parts, would order them... 🙂 jsut told them, "try to have this n that" 🙂

anyway, IS IT normal?? 10mV output of op-amp??? I can go ac coupled with that.. there IS space for 22uF on the board... man, dialup sucks! can even open photobucket yet...

 

[RX5]

here is the op-amp buffer I made.... still in debug mode....

An externally hosted image should be here but it was not working when we last tested it.

upper half of board is NE5532 + signal coupling caps.... lower half is boosted zener regulator....

 

[RX5]

after =========MUCH========= tweaking of this DIY UcD amp, made some measurements... Dc offset(speaker terminal) is -0.6mV.. input is NOT grounded... I just =muted= CD player headphone output volume.... note: no op-amp input buffer


=finally did it!!= ..... now almost all parts are cooler to the touch than before...

on the input buffer (NE5532), its works with UcD amp... BUT i cant still connect it with coupling caps bypassed.... need to tweak it STILL.... I GOT DC!! yuck!! YES, buffer provides addtl gain.. though I DID hear a -slight- difference in tonal quality... .... Its the only BEST op-amp I can find here.. but that dont bother me, as long as it works... still need some more tweaking (op-amp buffer) though.....

AND why I still dont use it with UcD??? boosted zener regulator for the op-amp HEATS!!! I used 2N5551/2N5401 ONLY!!! yes bad move 🙂 too small power a transistor... might as well use TIP31C and its PNP counterpart.... btw, supply for NE5532 is only +/-9VDC... but it works.. 🙂 I wish someone would send AD8620 as advance christmas gift.. hahah😀

worthwhile D-AMP to make... it never EVER wasted my time... and I learned a lot from it too... 😀

Regards,
Raff

 

[RX5]

GUYS,

just wondering..... AC(audio) coupling caps (auricap) between buffer AND input of barebones UcD??

what the difference anyway??

so.. where are those caps PLACED?? between signal source and AMP? or AMP and speakers??