Build an I M Distortion Analyzer.

Chapter 3   Parts Acquisition.

3.1 Flat Washers.
3.2 Ordering Parts From DigiKey.
3.2.1 5% Capacitors.
3.2.2 10% Capacitors.
3.2.3 Resistors.
 3.3 Insulating washers.
3.4 The Power Transformer
3.5 Parts List.
3.6 Something I couldn't find.
3.7 Other Parts and Supplies.
3.8 Tools.
3.9 Optional Distortion Reference.

Chapter 3 Parts Acquisition.

I have sent you to specific suppliers for a reason. However, you are free to buy from any supplier you wish. My reasoning has been to try to get as many parts as possible from one supplier. For example you may find some parts in the same category can be a little less expensive at supplier X and others at supplier Y. However, minimum order charges can quickly offset any price advantage. If you are really pinching pennies check out prices and minimum order requirements and make sure you are really saving money before you order.

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3.1 Flat Washers.

When you get to the point of installing the rotary switches you will find flat washers mentioned. If you try to buy 3/8 inch flat washers at your local hardware store you will find a washer which is too large in outer diameter and too thick. My searches on the web have turned up nothing. But if you buy pots from Circuit Specialists you will find that each of the three potentiometers comes with two flat washers under the nut on the bushing. As only one is needed to mount the pot the remaining three can be used for the three switches.

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3.2 Ordering Parts From DigiKey.

If you have experience with DigiKey you will not need any instructions on the use of their internet pages but if it is new to you, read on.

3.2.1 5% Capacitors.

Here is an example for the 0.022 uf 5% 50 V capacitor. The link will send you to the ceramic capacitors page. Then check off the boxes as follows.

  • Capacitance:   0.022 uf
  • Tolerance:   +/-5%
  • Voltage-Rated:   50V
  • Temperature Coefficient:   C0G, NP0
  • Mounting Type:   Through Hole

Then click the "Apply Filters" button. The table below where you are, contains a listing of all items that fit the parameters you have set. Watch out for that "Minimum Quantity" column. If it has a number like 1,000 in it the price will look pretty good but that's not what you can use. When comparing prices look for a 1 in that column. If I were you I would avoid the cheapest and the most expensive. Select one somewhere in the middle. To see the details of a particular item including quantity pricing, click on the "DigiKey Part Number". You may find that it will actually be cheaper to buy 10 instead of 8.

The parameters you selected will disappear from the screen when you click the "apply filters" button. The way to get them back is to click on the "Ceramic Capacitors" link in the upper-left area of the page.

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3.2.2 10% Capacitors.

As you might have guessed the 10% capacitors are not value critical. When applying parameters omit selecting C0G, NP0 from the "Temperature Coefficient" box.

3.2.3 Resistors.

Resistors work the same way as capacitors. The link sends you to the selection filter. To reset the filter click on the "Through Hole Resistors" link in the upper-left area of the page. Set the parameters as follows.

  • Resistance (Ohms):   The value you want.
  • Tolerance:   1% or 5%
  • Power (Watts):   0.25 W, 1/4 W
  • Composition:   Carbon Film for 5%, leave blank for 1%

Happy hunting.

3.3 Insulating washers.

Many of the parts I used were from my personal stock. The capacitors you buy will look different from the ones I used. I had insulated washers on hand and am shocked that no electronics supplier has them anymore. How do they expect us to insulate things from other things. As you will see below I did find them at a most unlikely place, Lowe's.

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3.4 The Power Transformer.

The power transformer I used is one I had on hand but is a rather standard transformer. It is a type that is classified as a filament transformer and is specified as 25.2 volts center tapped at a current of 1 Amp. I found a very nice looking one on MCM Electronics that was made by Triad. The dimensions weren't clear. They weren't accompanied by a mechanical drawing. It appeared that the transformer was a little large for this project. I kept looking and found one on Jameco which is listed in the table. It is listed as a 2 amp transformer but I doubt it would deliver that much current continuously. It is probably rated for intermittent service at that current. It is actually smaller than the one I used and is shielded to boot. In a transformer, size does matter and shielding reduces the ability of a transformer to get rid of heat. I would say it is more likely that the Jameco transformer is rated at 0.5 amps continuous duty. That's no problem because the current demanded by the analyzer is less than 100 mA.

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3.5 Parts List.

Parts List.
Chassis and Major Parts
Quant. Part Number Description Vender and its URL
1 P-HWCHAS1310BK Wood Frame with Black Aluminum Panel 13x10x3"
Go to Page		 Antique Electronic Supply
https://www.tubesandmore.com
1 P-HHW1310BKPL Extra Aluminum Panel for Above.
One supplied, you need two.
Go to page		 Antique Electronic Supply
5 P-H1590B Die cast Aluminum Box 4.37 x 2.37 x 1.22"
Go to page		 Antique Electronic Supply
1 102104 Transformer 115 v to 25.2 VCT @ 2 A
Go to page		 Jameco Electronics
Jameco.com
4 22-508 Prototyping Board
Go to page		 Jameco Electronics
Controls, Switches, and Connectors.
1 31VM405
50 K ohm Linear pot with switch
Go to page		 Circuit Specialists
circuitspecialists.com
1 31VA401 10 k Ohm Linear Taper Pot
Go to page		 Circuit Specialists
1 31VA601 1 M ohm Linear Taper Pot
Go to page		 Circuit Specialists
1 10WA365 2 pole 2 to 6 position high reliability switch
Go to page		 Circuit Specialists
2 10WA364 1 pole 2 to 12 position high reliability switch
Go to page		 Circuit Specialists
6 523-112424 BNC Connector
Go to page		 Mouser Electronics
http://www.mouser.com/
6 Knob, your choice of 5 styles.
Go to page		 Circuit Specialists
Semiconductors
14 1N4148 Small Silicon Diode.
Buy 20 and get a price break.
Go to page		 Circuit Specialists
4 1N4007 1 A 1000 PIV Rectifier
Go to page		 Circuit Specialists
5 78L15 Positive Reg 15 V 100 mA
Go to page		 Circuit Specialists
5 79L15 Negative Reg 15 V 100 mA
Go to page		 Circuit Specialists
5 TL072/CP Dual FET Op Amp
Go to page		 Jameco Electronics
3 TL074ACN Low Noise Quad FET Op Amp
Go to page		 Jameco Electronics
2 TL071CP Single FET OP Amp
Go to page		 Jameco Electronics
1 2N5951 2N5951 N Channel JFET.
Go to page 		Jameco Electronics
5% Capacitors
9 0.0033 uf 5% 50 V
Enter Values and Select		 DigiKey
8 0.010 uf 5% 50 V
Enter Values and Select		 DigiKey
8 0.022 uf 5% 50 V
Enter Values and Select		 DigiKey
5 0.033 uf 5% 50 V
Enter Values and Select		 DigiKey
10% Capacitors
1 C-TD022-630 0.022 uf 630 V
Enter Values and Select		 Antique Electronic Supply
44 0.1 uf 10% 50 V
Enter Values and Select		 DigiKey
2 31-200 470 uf 25 V Axial Electrolytic
Directly to Part Page		 MCM Electronics
1% Resistors
6 10 k ohm 1% 1/4 W
Enter Values and Select		 DigiKey
2 20 k ohm 1% 1/4 W
Enter Values and Select		 DigiKey
1 100 k ohm 1% 1/4 W
Enter Values and Select		 DigiKey
5% Resistors
6 560 ohm 5% 1/4 W
Enter Values and Select		 DigiKey
1 680 ohm 5% 1/4 W
Enter Values and Select		 DigiKey
1 WW3296-Y-1k 1 k ohm Trimming Potentiometer
Go to page		 Circuit Specialists
1 1.8 k ohm 5% 1/4 W
Enter Values and Select		 DigiKey
1 align="center">2.0 k ohm 5% 1/4 W
Enter Values and Select		 DigiKey
1 2.4 k ohm 5% 1/4 W
Enter Values and Select		 DigiKey
2 WIW3296-Y-5K 5 k ohm Trimming Potentiometer
Go to page		 Circuit Specialists
2 5.6 k ohm 5% 1/4 W
Enter Values and Select		 DigiKey
2 6.2 k ohm 5% 1/4 W
Enter Values and Select		 DigiKey
47 10 k ohm 5% 1/4 W
Enter Values and Select		 DigiKey
1 15 k ohm 5% 1/4 W
Enter Values and Select		 DigiKey
1 WIW3296-Y-2K 50 k ohm Trimming Potentiometer
Go to page		 Circuit Specialists
4 82 k ohm 5% 1/4 W
Enter Values and Select		 DigiKey
1 91 k ohm 5% 1/4 W
Enter Values and Select		 DigiKey
1 470 k ohm 5% 1/4 W
Enter Values and Select		 DigiKey
2 10 M ohm 5% 1/4 W
Enter Values and Select		 DigiKey
Hardware
*10 H354-ND 6-32 x 1/4" Machine Screw
Go to page		 DigiKey Electronics
*5 H360-ND 6-32 x 1/2" Machine Screw
Go to page		 DigiKey Electronics
*18 H368-ND 6-32 x 3/4" Machine Screw
Go to page		 DigiKey Electronics
62 KEY1033-ND 6-32 Hex Nut
Go to page		 DigiKey Electronics
5 7312K-ND #6 Solder Lug
Go to page		 DigiKey Electronics
30 S-HLW6 #6 internal tooth lock washer
Go to page		 Antique Electronic Supply
18 423534 #6 Insulating washer
Go to page		 Lowe's on line
lowes.com
A few inches. Copper Foil Tape with Conductive Adhesive
Go to page
You can probably do better on price on EBay.		 Amazon.com
1 106884 Lead Bender
Go to page		 Jameco Electronics
Optional: Distortion Reference.
1 P-H1590LB Die cast Aluminum Box 1.99 x 1.99 x 1.06"
Go to page		 Antique Electronic Supply
2 523-112424 BNC Connector
Go to page		 Mouser Electronics
http://www.mouser.com/
1 10WA364 1 pole 2 to 12 position high reliability switch
Go to page		 Circuit Specialists
1 10 k ohm 5% 1/4 W
Enter Values and Select		 DigiKey
1 30 k ohm 5% 1/4 W
Enter Values and Select		 DigiKey
1 91 k ohm 5% 1/4 W
Enter Values and Select		 DigiKey
1 240 k ohm 5% 1/4 W
Enter Values and Select		 DigiKey
1 680 k ohm 5% 1/4 W
Enter Values and Select		 DigiKey

* Sold only in lots of 100. I'll bet you need to stock up on screws anyway.

A note about the op amps.

When you order one of the TL07X series of IC many suppliers will substitute the LF3XX series. I have specified the TL07X ics for a very good reason. The LF3 series has higher noise and less bandwidth than the TL07 series. It might be a good idea to call your supplier of choice to be sure that they aren't going to substitute type numbers. Don't believe them if they tell you that they are the same. Evidence to the contrary is sitting on my bench at this moment.

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3.6 Something I couldn't find.

I used a control grounding lug as a ground point for one of the pots and one of the switches. Although I have a supply on hand it appears they are no longer available. I have devised an alternative method of grounding but it is represented only in drawings. The photographs show the control grounding lugs.

3.7 Other Parts and Supplies.

Other parts you will need are;
A couple of feet of number 14 solid copper wire, from the electrical department.
Roll of Scotch double stick tape.

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3.8 Tools.

Tools you will need. Buy, rent, or borrow, them if you don't have them. I recommend against steeling.
6-32 tap.
Tap handle.
Set of drill bits from 1/16 to ¼ in 1/64 steps.
Drill.
Miniature file.
If you don't have a band saw, or a friend with one, you should buy a hacksaw.
I strongly recommend the purchase of a Panavise. Buy the vice, the circuit board holder, and the base that clamps to the edge of your bench. Don't be tempted by the rubber suction cup base. I had one and got so frustrated with it that I threw it through a window. They only stick to vary clean plate glass.

The vise head is optional but the PC board holder is so handy you will wonder how you ever got along without it.

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