Sourcing electronic components for synth-DIY

Hardware

Eurorack frames

AKA Eurocard frames AKA IEC 60297 sub-racks. supermoduul.com have them cheap.

Connectors

0.145" / 3.68 mm pitch

Molex 1625 series. Used in the old Oberheim SEM.

Male pins

Molex 02-06-2103 (Digi-Key WM1000-ND, Farnell 1079887)

Receptacle for male pins, 3-way

Molex 03-06-2032 (Digi-Key WM1221-ND, Farnell 1593638)

Receptacle for male pins, 4-way

Molex 03-06-2042 (Digi-Key WM1222-ND, RS 679-4855)

Passives

Capacitors

Dielectrics

• http://www.interq.or.jp/japan/se-inoue/e_capa.htm
• http://my.execpc.com/~endlr/
• Capacitors: A Field Guide to Types and Habitats
• Understand Capacitor Soakage to Optimize Analog Systems
• _Capacitor characteristics_ by Rod Elliott

Potentiometers

The most common types of shaft are : round, 1/4" (6.35 mm) ; round, 6 mm; "knurled" a.k.a "serrated" a.k.a. "splined" (6 mm with 18 teeth) ; "D" (6 mm with a flat). Round shafts require knobs with a set screw. Knurled and D shafts accomodate molded knobs which are usually much cheaper.

Curves a.k.a. laws a.k.a. tapers : the three most common curves are linear, log (a.k.a. "audio") and anti-log (a.k.a. "antilog" a.k.a. "reverse audio"). In France (and, I believe, Europe), "A" means linear and "B" means log. In Japan (and, I believe, North America), it's the other way around. "C" always means anti-log.

One of the best deals there is on pots is the Alpha RV160 knurled shaft carbons. Rapid, Futurlec and Mouser sell them. Futurlec have the best prices. Mike points out that The pots from Rapid have longer spindles than those from Futurlec. If direct panel mounting the ones from Rapid, the spindles need cutting down..

Some people prefer G&H or Song-Huei's 16-mm carbon pots.

Beware of Piher pots. My experience has been that they become scratchy fast.

Anti-log pots

Anti-log pots are relatively hard to find. Banzai, Mouser and Small Bear carry Alpha anti-log pots (though Mouser don't seem to have any dual-gang ones). Before you embark on a search for an anti-log pot, read these :

• Tailoring potentiometers, from an article by G. Reinhold for Elektor 1979-12.
• The secret life of pots by R. G. Keen.
• Changing the Law of a Pot, from Beginners' Guide to Potentiometers by Rod Elliott.
• Java applet to plot the resistance curve of a pot with parallel resistor by Christopher List.

Centre-tapped pots

Tom Arnold has Alpha RV16 50 kΩ linear, centre-tapped, 1/4"-shaft pots for sale

Pots with push-pull switch

Mouser order code 313-1601F-500K is the Alpha RV16BF-10-15R1-B500K which is a 16 mm 500 kΩ linear carbon with a 1/4" shaft and a DPDT switch. Jürgen Haible used them in his Korg PS-3200 clone.

Precision resistors

• Rapid carry a good selection of BC Components MMB0207 precision resistors (metal film, 0.1%, ±15 PPM/K) for a very good price (£0.15 a piece).

Tempcos

Resistors with specific temperature coefficients (E.G. +3500 PPM/K as needed in exponential converters). See Ian Fritz's Dial-a-Tempco Exponential Converter.

• Akaneohm make an LT series of tempcos. Class G (2%) is standard, class F (1%) available upon request.

• Koa reportedly make an "LP" class F (1%) resistor. No idea where you can get them but Mouser carry many Koa references.

• KRL Bantry Components, inc. make tempcos from +80 PPM/K to +5000 PPM/K. They're not used to selling to individuals but they will deal with you if you have a large enough purchase : in 2005, "Metrophage" bought 600 USD worth of tempcos from them and got the prices down to 1.53 USD for the 1 kΩ and 1.77 USD for the 1.87 kΩ and 2 kΩ.

• Micro-Ohm make tempcos from +1000 PPM/K to +5100 PPM/K.

• Precision Resistor Company, inc. have +3500 PPM/K in stock. Other coefficients available.

• Tyco/Citec LT300014T261K0J (+3000 PPM/K but +3300 PPM/K available)

• Weltronic distribute Precision Resistor Company products in Germany.

Transformers

Audio transformers. OK, that's for general audio, not synth DIY.

• Cinemag
• Jensen
• Lundahl
• Neutrik
• Sescom
• Sowter
• Triad Magnetics

Reverb tanks

Accutronics

• Sound Enhancement Products, Inc. manufacture the Accutronics reverb tanks. They don't sell to individuals.

• Antique Electronic Supply in Tempe carry a selection of Accutronics reverb tanks.

• Banzai Effects in Berlin carry a selection of Accutronics reverb tanks.

• Saint Quentin Radio in Paris carry a selection of Accutronics reverb tanks, which they get from a company in New Jersey. They're open to ordering other models for you as long as they're available from their supplier. You may have to wait until their next order.

Belton

• Belton spring reverbs.

• Antique Electronic Supply in Tempe sell the Belton BL2AB3C1B.

Semiconductors

Oscillators & TOG

M108

• Neil Johnson has some for sale.

M110

Combined keyboard scanner and DCO. Outputs four square waves one octave apart which can be summed to approximate a sawtooth. Used in the Siel Mono and Jen SX1000.

• Neil Johnson has designed an M110 replacement based on an Atmel AVR ATmega8 MCU.

OTA

• Some info about OTA by Achim Gratz
• Secrets of OTAs by Jim Patchell
• A Short Discussion of the Operational Transconductance Amplifier by Gene Zumchak

CA3080

Harris/Intersil stopped making them (see under CA3280 below for details) but Rochester Electronics have taken them up and old stock is not hard to find.

• The Bridechamber : CA3080

• Futurlec : CA3080E.

• Rochester Electronics have CA3080 in stock and are now manufacturing new ones.

• Small Bear Electronics : CA3080A, CA3080E.

CA3280

• Intersil made the CA3280 and discontinued it in 2005.

  On 2005-05-24, Jim Patchell asked Intersil what the status of the CA3280 really was. Intersil support replied :

  No new dies were made after the Findlay plant closed in September 2002. LTB, Life Time Buy for the CA3080E and CA3080AE is 2005-09-15 or when stock runs out. Production of CA3080 and CA3080A wafers stopped when the Findlay plant was closed down September 2002 and we have been building units from die inventory ever since.

  On 2005-05-26, Don Tillman urged Intersil to keep the CA3280 alive. They replied :

  I will pass on your concerns but please understand, these CA family of products were developed by RCA on a very old and obsolete fab process that is long since been discontinued and the fab plant was shut down and sold off. We have been living on wafer stock. Today the wafer stock has been depleted to the point we have to withdraw the product. We need to insure we have enough product remaining to support the life time buys that are now incoming.

  So, we reluctantly must withdraw these CA parts as our stock is depleted and in good faith, notify our customer base in time for last time buys.

  Later, they added :

  We are sorry but what FAB equiptment we did not move to Florida, we sold with the building. The CA process was based on an old 7micron specialized process. So, the process is gone and is not worth the time and 10's of millions to rebuild when today we are working with sub micron processes. The market size for the CA part just will not return a profit for the cost.

  As for other sources, I would start with our obsolete distributor, Rochester Electronics [rocelec.com]. You might consider looking at Analog Devcices [analog.com], linear Technology [ltc.com] or Maxim [maxim-ic.com] for alternatives.

  Don Tillman's web log entry.

• Jim Patchell is now almost out of CA3280E.

• Rochester Electronics sell Harris-branded CA3280. Quoting James Gallant :

  The reason I brought the topic up is that I've found some at Rochester Electronics Inc. They have over 16,000 in stock spread between three part numbers, all of which are by Harris. I contacted them yesterday [2007-05-25], just before my first post on this topic, and they will sell to individuals. Their terms are $50 minimum order per line item. In other words, per unique part number ordered, not total order. They also take major credit cards for payment. The down side of this is that they do not list prices, you have to submit an RFQ, request for quote.

• Unicorn Electronics may have some.

LM13600/LM13700

• National Semiconductor make the LM13700. The LM13700A was discontinued in 1998. The LM13600 is also discontinued.

• New Japan Radio (JRC) make the NJM13600 and NJM13700. They're said to be equivalent to the original LM13600 and LM13700 as long as you don't exceed the rated differential input voltage.

• Digi-Key, Mouser and Small Bear Electronics sell

  Mfr	Mfr part no.	Pkg	Sup	SKU	Price
  ?	?	?	BC	LM13700	1+ $3
  NS	LM13700M/NOPB	SOIC16	DK	LM13700M-ND	672+ $0.51
  NS	LM13700MX	SOIC16	DK	LM13700MX-ND	2500+ $0.49
  NS	LM13700N/NOPB	DIP16	DK	LM13700N-ND	1+ $1.44
  NJR	NJM13600D	DIP16	DK	NJM13600D-ND	1+ $0.81
  NJR	NJM13600D	DIP16	Mou	513-NJM#13600D	1+ $0.63
  NJR	NJM13600D	DIP16	SBE	1520	1+ $0.75
  NJR	NJM13600M	DMP16	DK	NJM13600M-ND	1+ $0.81
  NJR	NJM13600M	DMP16	Mou	513-NJM#13600M	1+ $0.63
  NJR	NJM13700D	DIP16	DK	NJM13700D-ND	1+ $0.99
  NJR	NJM13700D	DIP16	Mou	513-NJM#13700D	1+ $0.77
  NJR	NJM13700M	DMP16	DK	NJM13700M-ND	1+ $0.81

• Farnell sell the National LM13700M/NOPB (SMT, order code 1150053) via Newark and charge 25 EUR for this service.

Don Sauer tells The LM13600/LM13700 story.

NE5517

The Philips fab in Caen where they were made burned down in December 2003. ON Semiconductor (Motorola) make an equivalent but, reportedly, it's not as good.

• ON Semiconductor make the NE5517/AU5517.

• Reichelt sell some NE5517. The web site does not state the origin but the ones I got were from ON Semiconducator, date code 0531.

VCA

BA6110

• Curetronic have some for 3.90 EUR each.

BA662

RIP

THAT 2162

THAT 2162 dual Blackmer VCA (QSOP only)

Profusion PLC and Mouser sell them.

THAT 2150A/2151/2155

Discontinued, replaced by THAT 218x.

THAT 2180/2181

• THAT 2180, pre-trimmed Blackmer VCA
• THAT 2181, trimmable Blackmer VCA

Profusion PLC and Mouser sell them.

Voltage references

FIXME Don't trust the grades in this table, they don't carry across manufacturers !

Transistor arrays

Pinout codes :

A

DIP-8, 2 × NPN : N1C N1B N1E nc nc N2E N2B N2C

B

DIP-8, 2 × PNP : P1C P1B P1E nc nc P2E P2B P2C

C

DIP-14/SOIC-14, 4 × NPN : N1C N1B N1E SUB N2E N2B N2C N3C N3B N3E SUB N4E N4B N4C

D

DIP-14/SOIC-14, 4 × NPN : N1C N1B N1E N2C N2B N2E SUB nc N3E N3B N3C N4E N4B N4C

E

DIP-14/SOIC-14, 2 × NPN, 2 × PNP : N1C N1B N1E SUB P1E P1B P1C P2C P2B P2E SUB N2E N2B N2C

F

DIP-14/SOIC-14, 2 × NPN, 2 × PNP : N1C N1B N1E P1E P1B P1C SUB P2C P2B P2E nc N2E N2B N2C

G

DIP-14/SOIC-14 : 4 × PNP : P1C P1B P1E SUB P2E P2B P2C P3C P3B P3E SUB P4E P4B P4C

H

DIP-14/SOIC-14 , 4 × PNP : nc P1E P1B P1C P2E P2B P2C P3C P3B P3E P4C P4B P4E SUB

I

DIP-14/SOIC-14, 5 × NPN : N1C N1B N1E/N2E N2B N2C N3B N3E N3C N4B N4E N4C N5B N5E/SUB N5C

J

DIP-16/SOIC-16 : 5 × NPN : N1C N2C N2B N2E SUB N3B N3C N3E N4C N4B N4E N5E N5B N5C N1E N1B

K

DIP-16/SOIC-16 : 3 × NPN, 2 × PNP : N1B N1E N1C N2E N2B N2C N3E N3B N3C P1E P1B P1C P2E P2B P2C SUB

L

6-lead TO-71, 2 × NPN : 1=Q1C 2=Q1B 3=Q1E 5=Q2E 6=Q2B 7=Q2C

M

6-lead TO-78, 2 × NPN : pinout same as L

N

6-lead TO-99, 2 × NPN : pinout same as L

O

6-lead TO-71, 2 × PNP : pinout same as L

P

6-lead TO-78, 2 × PNP : pinout same as L

David G. Dixon 2009-12-05 : [...] the Linear Integrated Systems LS358 log conformance matched pnp [is] an excellent candidate for expo converter applications [...] Linear has two distributors: Trendsetter in Texas and Nacsemi in Florida. Canadians can also obtain Linear parts from and Eli Manis in Quebec. Linear also ships direct. As far as I can tell, none of these suppliers have minimum order policies. Trendsetter likes to see orders of at least $50, and Linear of at least $100 (which shouldn't be hard). Eli Manis didn't mention any minimums, and seemed genuinely eager to help, as did they all.

Bulk resistance (r_BE) comparison by René Schmitz.

Parts to look into : Philips BC847BS and BC857BS, Zetex ZTX795A and ZTX1151A, 2SA798, 2SC1583, 2SC3381, 2SA1349, CA3045/LM3045, HFA3128.

Logic

Logic Threshold Voltage Levels explains the difference between 4000-series or 74C and 74HCT.

Vactrols a.k.a. optoisolators

An LED and a photoresistor in the same package, forming a voltage controlled resistor. Useful for adding voltage control to a circuit.

• EG&G Vactec / Perkin Elmer make the VTL5C1 through VTL5C10.

• Silonex make the NSL-32 family. Reportedly faster than the VTL5Cx.

Some (most ? all ?) types of photoresistors contain cadmium sulphide (CdS). Cadmium is one of the substances banned in the EU under RoHS. There used to be an exemption for "cadmium in photoresistors for optocouplers applied in professional audio equipment" but it has run out on 2010-01-01. As of 2010-01-13, Rapid still sell the VTL5C6, though.

• Allied Electronics sell the entire Perkin Elmer VTL5Cx range.

• Farnell sell some VTL5Cx and NSL-32 (E.G. order code 3168-773).

A. Documentation

• Scott Gravenhorst's parts substitution page
• Scott Gravenhorst's preferred components page
• Aaron Lanterman's synth DIY datasheet and ap note collection
• Roy Tellason's data sheet collection
• common parts in synth DIY

B. Manufacturers and resellers

Specialised stores : The Bride Chamber, Electronic Schematics for Hobbyists, Kevin "Synthfool" Lightner, Pedal Parts Plus, Doug Terrebonne at synthparts.com, TubeAmpDoctor and Senso at Vintage Planet.

Cross-vendor search :

• http://www.findchips.com/ (North America)
• http://burnit.co.uk/sdiy/part_search.php (UK/US)
• http://octopart.com/ (US)

General electronic components resellers : E44 (mail order + stores in Nantes, Poitiers, La Roche-sur-Yon and Vannes), ECE espace composants électroniques (mail order + store at 66 rue de Montreuil 75011 Paris), RAM/Verdier SA/Zeus (mail order + stores in Paris) and RS Components (known as Radiospares in France, formerly Verospeed). ESR Electronic Components Ltd near Newcastle.

Allied Electronics

Their web site lists a number of shipping methods :

UPS Next Day
UPS 2nd Day
DHL Next Day Noon
DHL Next 10:30 AM
DHL Saver - Next 3 PM
DHL 2nd Day
Fedex Standard
Fedex Priority 1
Fedex 2nd Day
U.S. Express Mail

The cheapest is Express Mail. There is no ground delivery.

If you choose Express Mail as I did, the delivery guy will collect the VAT and handling charge. Have some change ready.

Farnell

Until a couple years ago, Farnell France would only deal with businesses. They will now sell to individuals. There is a minimum order and you will pay shipping but it's very reasonable.

Futurlec

There are sometimes delays but the goods usually do arrive.

Mouser

A few things you might want to know before ordering from them :

• If you live in France and chose FedEx International Priority shipping, you will get a bill from Coface for VAT and fixed handling charge (7.20 EUR + VAT).

  This invoice will arrive about two months after the corresponding parcel. If you are running a group buy, you need to anticipate this. If you bill participants solely on what Mouser charged you, you will lose money.

  Apparently, Coface is involved only because of FedEx's policy to off-load their "debt collection" to them. A similar policy may be in effect in other countries.

• Just because Mouser's web site says a reference is in stock does not mean it is. After placing the order, you may get an email advising you that references that were "in stock" when you clicked on the button are now "this product is expected to be in stock by" various dates as far as five months in the future.

  This is bad because it means another shipment. Even if Mouser pay the postage on the second parcel, Coface will bill you another 7.20 EUR + VAT. My last Mouser order was split in four. The last shipment was for 2.40 USD of chips. I asked Mouser to cancel it as I would rather lose 2.40 USD than 7 EUR.

• After placing your order, you may get two emails referring to two different orders. If the second email says "WAIVE SHIPPING SPLIT ORDER", don't panic. It happened to me ; my 170-entry order was split into two 85-entry orders because it "didn't fit", whatever that means. Perhaps there is a 100-entry limit or weight limit.

  Of course, that means an extra 7.20 EUR + VAT for dear old FedEx-Coface.

Rapid

Rapid are funny. They ship orders in reused cardboard boxes. They seem to try to carry as few items as possible and be cheaper than everybody else. They are the anti-RS. If their headquarters came in contact with those of RS, they would probably annihilate each other, converting all their matter to energy.

They used to have a very stiff minimum order of 500 UKP for people outside of the UK. As of 2008-01, that is a thing of the past : their web site says Export orders to countries outside the EU have a minimum order value of £25. No minimum order value within the EU..

They do have a maximum order of sorts, however. If you try to place an order for more than 250 GBP (including shipping and VAT), their web site will make it look like it worked but the next day, you will get an email advising you that "for security reasons", they cannot take credit card and so you must pay via bank transfer. This not only means a 12 GBP fee, but complications with any "end column day" deals and/or items going out of stock in the meantime.

RS Components / Radiospares

Formerly known as Verospeed.

Beware of order codes beginning with 25 or marked as "Newark InOne". There is an additional charge of 15 to 25 EUR on those.

Historically, Radiospares would sell to individuals with a small (or no) minimum order. Sometime in 2005 or 2006, they started enforcing a 150 EUR minimum order for individuals. So not content with being more expensive than Farnell, they are now also harder to deal with.

Update : as of 2009, it seems their terms have changed again. There is no minimum now but

• orders under 100 EUR are charged 10 EUR extra,
• orders between 100 and 150 EUR are charged 5 EUR extra,
• you have to order by phone,
• you are restricted to part of the catalogue (what part, their web site does not say).

At least this is the case for their French branch.

C. Acknowledgements

Most of the information on this page comes from synth-diy subscribers. (Archives : http://dropmix.xs4all.nl/pipermail/synth-diy/ (from 2007-03 on), http://search.retrosynth.com/synth-diy/ (from 1995 on))

This is http://www.teaser.fr/~amajorel/sourcing/, last modified 2010-05-18.