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Author Topic: DIY amp directions  (Read 46289 times)

Roly

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Re: DIY amp directions
« Reply #15 on: September 07, 2014, 01:57:22 PM »
Quote from: Lauren
Just got back from RadioShack

Why do I suspect that they'll remember you?   ;)


Quote from: Lauren
I bought a big bag (500!) of Carbon-Film Resistors

See?  I warned you it was addictive.  Now you are going to have to build him a whole line of stomp boxes to use up this excess.


Quote from: Lauren
10K Linear Pot

After their value and taper (log or lin) pots are generally selected on their mechanical properties, how and where you intend to mount them.  In this case you need a VCU-style with a mounting nut and shaft for a knob.  Sometimes these come with excess shaft and you have to cut them to the required length.  The 1k pot should look identical except for its value marking.  Pity they didn't have in stock.








Quote from: Lauren
Could not find the transistor.   :(


I think you need to find another store, maybe open a mail order account with Mouser or someone.

The MPF102 is as common as dirt, but just about any N-channel J-FET should substitute.


Quote from: Lauren
Purchased the .047uF 50WVDC, 100uF 35WVDC, 220uF 35WVDC, and just realized I didn't buy the .1uF.  >:(  How do I tell the voltage rating?

The smaller values are electrolytics which are polarised - like the IC and the FET you have to get them in the right way around, the smaller values are just normal caps.  "35WVDC" - maximum Working Volts DC.  Generally we buy the voltage range that is next up from where we are working, but 35V should be fine.  The lower values are typically 100V working so they are no problem.


Quote from: Lauren
red LED light

A note of caution.  A LED is a diode, not just a light globe, and it must have a suitable resistor in series with it to limit the current.


Quote from: Lauren
22 Gauge Stranded wire (they didn't have 24...is this ok??)

In some projects such as a 100 watt amplifier where there can be a fair bit of current flowing the wire gauge used can be important.  For this project we only need it to connect X with Y in a reasonably robust manner - thick enough to last well, thin enough to work easily.  Your local computer shop will typically have a few dead computer power supplies kicking about waiting to be thrown out which are generally free of the asking.  A few of these will provide you with enough coloured hookup wire to last years (unless you go really manic on building).


Quote from: Lauren
a small general purpose printed circuit board (the thing I am most uncertain is right). 

This;


...or something similar.  $2.50 for the pair.  I know you have some startup costs such as a soldering iron, but $80 seems like a lot to me.

All those resistors, how do you tell them apart?  Well look on line for one of the many resistor colour code charts and download a couple.  Initially at least you are going to need this to find your required value resistors in your mega-pack.

You will notice that resistor values are not arbitrary but follow a (rather odd) sequence; 1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 4.7, 5.6, 6.8, 8.2, 10.  After a while you get to recognise the colour patterns instantly on sight.  The three colours red/orange/yellow (2, 3, 4) can sometimes be confused when they are multipliers; when in doubt measure it with your trusty $10 digital multimeter (remembering to hold only one end, you have resistance too).


Quote from: Lauren
I am still missing the 10K Pot, the MPF102 Transistor, and the .1uF Capacitor.  Hopefully I can get started with what I have??

It would be better to have all the board-mounting bits, FET and cap, before you start because retrofitting parts can be a bit of a wangle, but you can certainly start marking up your board with a fine felt tip pen as you nut out where each component should go.  Generally we start with the IC or its socket and build up around that.

Have you watched some YouTube soldering How To's?  You also need some a little practice on something harmless before you start.

I must confess to being a tad excited myself - love a good build thread.   :dbtu:
If you say theory and practice don't agree you haven't applied enough theory.

galaxiex

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Re: DIY amp directions
« Reply #16 on: September 07, 2014, 08:39:02 PM »
As a 'beginner" I am following this with interest.  <3)

Just a note, I checked Mouser and DigiKey for the MPF102 and both show it as obsolete and no stock.

As Roly said, just about any N channel JFET will substitute. The PF5102 is in stock at Mouser and DigiKey.

Others that would probably work are J-111, J-112, 2N3819 etc.

If you really want to stick with the MPF102, Jameco has it.  :)

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_26403_-1

Edit;
Amazon has it too in a lot of 6.

http://www.amazon.com/MPF102-FET-Transistor-6-pieces/dp/B007V4FS5U/ref=cm_cr_pr_product_top

« Last Edit: September 07, 2014, 09:28:32 PM by galaxiex »
If it ain’t broke I’ll fix it until it is.

Roly

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Re: DIY amp directions
« Reply #17 on: September 08, 2014, 05:28:56 AM »
As I recall 2N3819 is the "proper" type number for the (Motorola in-house) MPF102, but those J-series should work just as well.  {But what does it mean to say they are the "same" when they have a 10:1 spread in their specs?}

Quote from: galaxiex
Amazon has it too in a lot of 6.

For her next project?  May as well since she's got a bag of 500 resistors.  :lmao:

But serriously, if you are going to buy in quantity you can get some serious discounts from 25-up.  Every component I buy I buy 2, 5, or 10, depending, cos as Jeri Ellsworth says, you can't have too many parts (or multimeters, or oscilloscopes or...).


Parts packs are a good way to get started with a stock of components, and some things such as transistors in 100 packs like;
http://www.jaycar.com.au/productView.asp?ID=ZT2170


NPN and PNP PN100 and PN200 "universal" transistors, 30c ea or 21c in 50+.  100 transistors (for only $20) will keep you building pedals and preamps for an awfully long time.
If you say theory and practice don't agree you haven't applied enough theory.

g1

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Re: DIY amp directions
« Reply #18 on: September 08, 2014, 02:16:52 PM »
  Just a few more comments to add to what others have mentioned.
Lower gauge number wire is thicker, so it will always be able to handle the current, but may be stiffer and more difficult to work with, in this case I think 22ga will work fine instead of 24.
  A 1K trimmer is not a switch, it is a trim pot.  Generally, trimpots are miniature versions of pots that are adjustable with a screwdriver rather than a knob.
  Pretty much any .1uF cap  will be rated at least for 16V, so any should work.
Big bags of assorted parts are not always a good value, some times there may be 3 useful ones and a hundred you will never use.  In this case, I don't know how many different values of resistors they have in that assortment.  If it's a lot, you will have a hard time sorting through all those color codes to find the ones you want.

And I agree with Roly, $80 seems quite high.  Could you do a breakdown of the more expensive items?  If some are ridiculous, perhaps you could take them back and get them elsewhere.  I had thought this would be quite a cheap project, if a lot of it is general supplies not specific to this unit, then that is more understandable.

Lauren

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Re: DIY amp directions
« Reply #19 on: September 08, 2014, 05:44:03 PM »
So this is what I have purchased so far:

Bag of Resistors: $14.49 (photo attached)
10K Linear Pot: $3.99
LM386: $1.99
.047uF Capacitor: $2.49
100uF Capacitor: $1.49
 220uF Capacitor: $1.49
Mono Quarter Inch Jack (Out): $4.49
Stereo Quarter Inch Jack (Input): $4.49
LED light: $1.99
Battery Snaps: $2.99
9 Volt Battery: $4.99 (but it was a BOGO, so more like $2.50 :) )
PC Board: $2.49
Wire: $8.49 (3 25' rolls)
DeSolder Braid: $4.49
Rosin-Core Solder: $5.99


I still need to buy a few things--1 pot, 1 transistor, and 1 capacitor.  So far, I have spent $66 on the things I will use for this project, but also bought a couple of doubles (PC Board, batteries), which added to that $66, take me closer to $80 with the tax.  I'll be able to use the soldering parts later on and my tons of resistors!  We already have a soldering iron and a multimeter, so that's good! 

Hoping to find the remaining parts soon so I can get started!  Keep the advice coming!



« Last Edit: September 08, 2014, 05:49:51 PM by Lauren »

Lauren

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Re: DIY amp directions
« Reply #20 on: September 08, 2014, 05:45:12 PM »
Also need to buy a speaker, which I keep forgetting to factor in!
« Last Edit: September 08, 2014, 05:49:31 PM by Lauren »

Lauren

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Re: DIY amp directions
« Reply #21 on: September 08, 2014, 05:58:11 PM »
And this is the Circuit Board I purchased.  Will it work?

galaxiex

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Re: DIY amp directions
« Reply #22 on: September 09, 2014, 12:24:47 AM »
That circuit board will work fine.
A bit big maybe, but that gives you lots of room to have an "airy" layout.
It's easier to place parts and work with a big board than too small a one.

Once you have everything...
Test place the parts without solder first, following the diagram to see how things connect.
You may end up re-arranging thing so they connect easier.
I sometimes "stuff" the board several times without solder.
After looking at a parts layout for awhile I will often change it to make certain connections easier.

I think? this project has a suggested board layout at http://www.runoffgroove.com/ruby.html
ahh, yes it does. Their board is a little different in that it only has individual solder pads.
But the "packaging" on that board is pretty tight. (that's not a bad thing.)
On your board you could spread things out a bit if you wanted.

Hope you find your parts soon.
I'm excited to see what you build.   8)

Many here stand ready to help if you have trouble.
Please don't be afraid to ask.  :)
If it ain’t broke I’ll fix it until it is.

Roly

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Re: DIY amp directions
« Reply #23 on: September 09, 2014, 11:21:55 AM »
The resistor pack looks like a really good assortment of values, and they are in belt-lettes so once you work out a colour code for a value you can write it on the cardboard end.  I sort mine into a plastic fishing tackle storage box divided in decade ranges.

Circuit board, also just fine ('tho you may have to change the layout a bit to fit in with those 3-hole bars.  I'll check.

galaxiex - what can I add?
If you say theory and practice don't agree you haven't applied enough theory.

galaxiex

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Re: DIY amp directions
« Reply #24 on: September 09, 2014, 12:12:10 PM »
Oh, one of these are indispensable.....  :)

 Use it to hold solder joints, the circuit board, many things.... available everywhere...



http://en.wikipedia.org/wiki/Helping_hand_(tool)

Many other uses besides soldering.

Get one with or without the magnifying glass.
I have both...  :loco
« Last Edit: September 12, 2014, 02:15:09 AM by galaxiex »
If it ain’t broke I’ll fix it until it is.

Roly

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Re: DIY amp directions
« Reply #25 on: September 09, 2014, 12:24:53 PM »
{well it was this or Solitaire   :loco }

Quote from: Lauren
Bag of Resistors: $14.49  (500off)
10K Linear Pot: $3.99
LM386: $1.99
.047uF Capacitor: $2.49
100uF Capacitor: $1.49
 220uF Capacitor: $1.49
Mono Quarter Inch Jack (Out): $4.49
Stereo Quarter Inch Jack (Input): $4.49
LED light: $1.99
Battery Snaps: $2.99
9 Volt Battery: $4.99 (but it was a BOGO, so more like $2.50 :) )
PC Board: $2.49
Wire: $8.49 (3 25' rolls)
DeSolder Braid: $4.49
Rosin-Core Solder: $5.99

Jaycar in AU$

 1 / 4 Watt Carbon Film Resistors - 300 Pieces
This pack includes five of virtually each value from 1 Ohm to 10 Meg. Sixty different values. All resistors are bandoleered for easy sorting. Values supplied are 1, 1.5, 2.2, 3.3, 4.7, 5.6, 10, 12, 15, 22, 27, 33, 39, 47, 56, 68, 82, 100, 120, 180, 220, 270, 330, 470, 560, 680, 820, 1k, 1k2, 1k5, 1k8…
Qty
1+ $6.95 * 500/300 = $11.58  < corrected for quantity


10K 16mm Potentiometer Linear Single Gang (B)
Qty
1+ $1.95

(OR)

10K 24mm Potentiometer Linear Single Gang (B)
Qty
1+ $2.25


 LM386N-1 Low Voltage 1W Amplifier Linear IC
Qty
1+ $2.25


 0.047uF 50V Blue Chip Monolithic Capacitor
Qty
1+ $0.28    (even at 630 volt they are still only $0.85)


 Capacitor Electrolytic 100uF 16V 105C L / ESR
Qty
1+ $0.36


 220uF 16V RB Electrolytic Capacitor - 105oC
Qty
1+ $0.35


 6.5mm Mono Chassis Socket - Unswitched
Qty
1+ $1.95
 6.5mm Stereo ENCLOSED INSULATED SWITCHED Socket
Qty
1+ $3.45
 6.5mm Stereo ENCLOSED SWITCHED DPDT Socket
Qty
1+ $2.95


 Chrome Bezel with 5mm Blue LED
Qty
1+ $4.95


 9V Battery snap - Standard
Qty
1+ $0.40
 Safety 9V Battery Clip - Highest Quality
We call these safety clips because the side of the clip totally covers the battery terminals and sits flush on the top of the battery. Supplied with high quality AWG24 connection cable.
Qty
1+ $0.90

(Battery - too many variables)

 Universal Pre-Punched Experimenters Board - Small
…stock 3 sizes of Phenolic board that has a matrix of punched holes on a 0.1" (2.5mm) pitch . Each donut is separated from its neighbours by about a 0.5mm gap. This effectively isolates each pad but also makes it easy to bridge solder across to make interconnections. Each board also has `fingers' on opposite…
Qty
1+ $4.50


Hook-Up Wire Pack - 2 metres
2 metres of 8 different colours of 13 x 0.12mm hook- up wire.16 metres in all.    
     QTY    
     1+    $4.95  * 22.86/16 = $7.07  < corrected for length


 3mm Economy Desolder Braid
A special treted piece of braid for removing solder from a PCB. Place the braid over the solder and apply soldering to efficiently remove solder. 3mm wide 5" long! more...
Qty
1+ $3.25


Rosin-Core Solder - (depends on quantity, also Pb-Directive complicates)


Radio Shack
14.49+3.99+1.99+2.49+1.49+1.49+4.49+4.49+4.99+2.99+2.49+8.49+4.49=58.37 (US$)

Jaycar
11.58+1.95+2.25+2.25+0.28+0.36+0.35+2.95+4.95+0.40+4.50+7.07+3.25=42.14 (AU$)

At this particular instant 1 Australian Dollar equals 0.92 US Dollar

AU$42.14 * 0.92 = US$38.77

My experience of Tandy (which was RS in Australia before they went bust) is along these lines, close but more expensive, and in the case of small individual components like caps, way over the top, but overall typical.  I wouldn't be surprised if you did a similar comparison with Mouser, DigiKey and other US suppliers you would find a similar difference.  You haven't been too badly gouged, and you seem to have obtained most of what you need, but Tandy/RS here had a pretty awful reputation of selling overpriced crap ('tho I believe the quality in RS stores in the US is better).


If you buy a sewing machine you better come up with some clothes, and if you have a pack of 500 resistors you better be planning a fuzz box or two to go with his new amp.   :lmao:
If you say theory and practice don't agree you haven't applied enough theory.

g1

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Re: DIY amp directions
« Reply #26 on: September 09, 2014, 02:14:37 PM »
 Ok, that resistor assortment looks much better than I expected.  I was worried there might just be 500 individual resistors thrown in a bag for you to sort out.  Looks like they are separated by value, with more of the most common values.  Price is reasonable, the only thing to keep in mind is they are 1/4 watt, which is fine for any battery operated device, but may not be useable in some other powered circuits you may build in the future.

Most of those prices you paid are fairly reasonable, except for the very generic individual electronic components, like the caps, led, and battery snaps.
It's fine for a one off project, but if you do more building check an actual electronic supplier such as Mouser, Newark, Digi-key, etc.
  As Roly pointed out, simple items like some of those caps are inflated 10 to 100 times for price.


Roly

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Re: DIY amp directions
« Reply #27 on: September 10, 2014, 03:46:12 AM »
{please scrute for errors guyz}
If you say theory and practice don't agree you haven't applied enough theory.

Lauren

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Re: DIY amp directions
« Reply #28 on: September 10, 2014, 06:05:37 AM »
You. Are. Awesome.

galaxiex

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Re: DIY amp directions
« Reply #29 on: September 10, 2014, 08:47:20 AM »
We just want to see you (successfully) build it.  :)
But...
Roly already warned you...
Once you drink the Kool-Aid there is no going back.  ;)
If it ain’t broke I’ll fix it until it is.