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noob needs help with schematics (cmoy)

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wavid

New Member
Hey guys..me and my dad have started bonding more recently and its his birthday in a few days and i want to make something with him...
he bought me some parts to make a Cmoy headphone amplifer...but the tutorial on the website has a differnt board...so i cant follow the tutorial ....instead i will have to make it by looking at the schematics...
ive never made anything like this before but really want to learn and this will be a great step into DIY electronics...
if some1 could help me set this up so that me and my dad can build this i would really appriciate it...
ok so..here are the schematics
http://www.electro-tech-online.com/custompdfs/2009/07/cmoy-tangent-sch.pdf

THESE ARE MY PARTS

the pic shows
2 electrolyrtic caps 200uf 25v
2 0.1 uf polypropylene film caps (the blue ones) on them it says 400v 100nk :S
dual op amp
and the board

i didnt include the rest of the parts in the picture but are as follow
1x 10 KΩ 1/4 W metal film resistor
2x 4.7 KΩ 1/4 W metal film resistor
2x 100 KΩ 1/4 W metal film resistor
2x 1 KΩ 1/4 W metal film resistor, gain 11
and LEDS and switchs etc

basicly in the picture the board is very different so i cant just follow the instructions and the parts will be in different places...but i cant figure out where....


if some1 could draw me a diagram maybe of where each part should go
i would really appriciate it!....i really want this to work
 

Wp100

Well-Known Member
Hi,

One thing missing from the circuit diagram is the pin connections for the IC, if you search / download the datasheet for the chip that will show them.

You really need to do this yourself and enjoy the learning process - start by printing out the circuit diagram then just lay the parts on their respective components on the diagram so you become familiar with them all.

This will hopefully make it easier for you to see how to build them onto the strip board. Just fit the parts through the holes on your first try - don't solder them yet as you will probably need to reposition them at some stage.

Before you fit the ic into the socket, connect the batteries and test with a multimeter that you are getting the correct voltage on the correct pins - if ok, disconnect the power and fit the chip.


If you get stuck, show us what you have done and we will try and help you out.
 
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Hero999

Banned
It doesn't even give the part number of the IC.

All I can say is that a normal op-amp won't do because it won't be able to drive low impedance headphones.
 

wavid

New Member
here is what ive got so far...
notice the 2nd 0.1 uf polypropylene film cap at the top
its supposed to be to the left of the dual op amp...
but thers nowhere to put it...
will it work if i put it where it is and link it with jumpers?
never done anything like this before so need advice plz


also i have 2 spare 220uF 63v electrolytic caps
can i use them for anything?

so my op amp is wrong?
i just bought wat was on the parts list....
does anyone have any sujjestions before i put it together?

btw im going to be using Sennheiser 280s
 
Last edited:

whiz115

Member
here is what ive got so far...
notice the 2nd 0.1 uf polypropylene film cap at the top
its supposed to be to the left of the dual op amp...
but thers nowhere to put it...
will it work if i put it where it is and link it with jumpers?
never done anything like this before so need advice plz


also i have 2 spare 220uF 63v electrolytic caps
can i use them for anything?

so my op amp is wrong?
i just bought wat was on the parts list....
does anyone have any sujjestions before i put it together?

btw im going to be using Sennheiser 280s
you never told us what's your op amp...you only say dual op amp...
but if you got the number from the part list then i guess it's fine.

you can arrange the components on the pcb as you like...but you
should connect them as the schematic details describe..

keep the spare for a future project.
 

wavid

New Member
i dont understand...the pins? ther are 8 pins :S
will this op amp be ok then?



thanks so much for the help btw everyone :)
 
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whiz115

Member
how are you going to connect these 8 pins the way the schematic describes?
do you know what is what?

will this op amp be ok then?
your op amp is pin compatible with the ones the part list specifies...
this means it should work..but not all characteristics are the same
 

wavid

New Member
i dont know...im very new to this so i just followed the diagram from cmoy website
the opamp was a chip with 8 pins that instered into anouther black thing that i then inserted into the board
what am i doing wrong at the momment? and what can i do to improve wat im doing?
 
Last edited:

whiz115

Member
i dont know...im very new to this so i just followed the diagram from cmoy website
the opamp was a chip with 8 pins that instered into anouther black thing that i then inserted into the board
what am i doing wrong at the momment? and what can i do to improve wat im doing?

first thing your strip board doesn't look exactly the same as the one the site and you also said something about changing components position so if you're going to rearrange the components on then you can't follow the assembling instructions as they are on the site so you need to know what each pin of the op amp does so you can follow the schematic.

these details can be found on a datasheet

http://www.fairchildsemi.com/ds/NE/NE5532.pdf
 

solis365

New Member
First order of business:

Those giant blue capacitors you have that say 400V on them are definitely not necessary. You probably want some 0.1 uf or 100nf small-signal type capacitors, like a ceramic type.
(0.1uf = 100nf this is probably what the 100nk means on the capacitor, no idea why they use k). You will also save space by switching. I'm not sure if they will work properly either, if theyll degrade the signal or something of that nature. Someone else weigh in on this?

Second order of business:

the schematic on the website shows an opamp with split supply rails - +9V and -9V. The datasheet for wavid's opamp shows Vcc and GND, a single-ended supply. so is this chip really compatible with the one recommended on the site?

IF IT IS NOT COMPATIBLE: try your best to get the exact opamp shown on the site.
IF IT IS:
the datasheet for the chip is linked above. it has a picture of the chip on the first page with the pin numbers. there will be a small circle imprint on your chip, this will indicate pin 1 so you can follow the picture properly. drawn on top of the chip are the schematic symbols for each opamp on the chip. so look at the schematic and look at the picture in the datasheet and see how it all goes together. You will notice that the schematic shows the opamp (triangle) having 5 wires, while the datasheet only shows 3. The two vertical wires represent the power supply connections to the opamp. this is equivalent to the Vcc and GND pins on the chip. when building both channels, you will only need to make the connection to the chip once. the chip has the connection to each opamp already there inside.



about the difference between the boards:

his tutorial has some little tricks for through-hole layout that help make the final product compact and tight-together. since you have a different board, all you need to do is make the connections right. the silver pads on the board are metal, and so they will connect parts together and reduce the need for you to put in jumper wires, which are messy. On the schematic, a line just means a metal connection between components. so using the metal pads on the board and a few jumper wires, see if you can wire everything up. you might get somewhere and not have room for a part, so youll need to rearrange a little and try again. youll probably learn quite a bit about how to hook up parts on a protoboard/breadboard, as the metal pads on this are very similar to the way breadboards are connected.

heres a tip to keep you from frying your chip:
the chip plugs into a little black plastic socket, which you have. remember above when i talked about the circular indent that will tell you pin 1 of the chip? put the chip in the socket. now, carefully, put a dab of white-out on the circle to make it easy to see (dont get white out on the metal pins. if you do, scratch it off carefully and try again.) on the outside edge of the plastic socket, also put a small dab of white-out, near the corner where the circular indent is. (dont get white out on the inside of the socket or on the metal pins). let the white-out dry and carefully take the chip out of the socket. now you can put the socket in the board without the chip and remember which way the chip was in. the only purpose of the socket is to let you keep the chip away from the board when soldering (so you dont overheat it) and to let you swap a new chip in if you accidentally fry the first one. so you can just pretend the pins on the socket are the exact same as those on the opamp chip.

i can give some tips for wiring the board efficiently if you like, i will post a picture and an explanation later. but you should figure out where to put the parts yourself!

another tip: keep all wire lengths as short as you can, long wires will increase the possibility of unwanted oscillation.
 

whiz115

Member
First order of business:

Those giant blue capacitors you have that say 400V on them are definitely not necessary. You probably want some 0.1 uf or 100nf small-signal type capacitors, like a ceramic type.
it depends... if you're audiophile then the 0.1 uf polypropylene film caps he bought are fine... if you aren't then you go for smaller ones so you can save space.


the schematic on the website shows an opamp with split supply rails - +9V and -9V. The datasheet for wavid's opamp shows Vcc and GND, a single-ended supply. so is this chip really compatible with the one recommended on the site?
what does "Power Supply Voltage VCC ±22V" and "Input Voltage Range ±12V" means?
 

marcbarker

New Member
First order of business:

Those giant blue capacitors <..> I'm not sure if they will work properly either, if theyll degrade the signal or something of that nature. Someone else weigh in on this?
They'll be fine, don't worry about it, really. Also give the unit some extra weight won't it?

I think (my opinion) the discussion is getting far too technical for someone who's never picked up a soldering iron before, let alone knows what an IC is! (i.e. single/double ended powersupplies, wire length and oscillation)

I say the supply as shown on the original data is done OK, and the opamp is OK too. The circuit would also probably work fine with just one battery not 2.

The good thing about square 9 V batteries is that in practice the cheap ones you use for testing with, generally don't produce enough power to blow up ICs, not unless you're unlucky. If you'd put the power on backwards, the IC just gets hot that's all.
 

chilinski

New Member
I suggest building this on a breadboard first so you get some idea how the wiring should work. That will make a lot of things understandable and give you some easy options to move wires around, swap different parts, etc. before soldering it. You can try different capacitors, different resistors for different gain levels and even switch to other ways of dividing the voltage.

I built several of these from the tangentsoft site, and they have all worked extremely well. I did them first on the breadboard because some of the stuff on the site didn't make sense until I actually started to connect parts together. If you use a breadboard, you won't have to do desoldering, which can make a real mess of your board and give you all kinds of improper connections, shorts, etc.

By the way, I had a TL082 explode when the voltage was reversed. Loud POP! A little smoke and that was it for that chip.
 
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