Search found 112 matches

by loki
Sat Jan 02, 2021 8:47 pm
Forum: Music Tech DIY
Topic: TL074H??
Replies: 20
Views: 519

Re: TL074H??

Give the OPA1678/9 a look in comparison.
by loki
Wed Oct 28, 2020 5:18 pm
Forum: Music Tech DIY
Topic: Understanding suitable transistor and opamp substitutions
Replies: 28
Views: 773

Re: Understanding suitable transistor and opamp substitutions

I recommend that everyone interested in classic synthesizer circuits download: the National Semiconductor Discrete Databook 1978, available from the internet archive. It catalogs the different processes and their associated part numbers. It will help you understand that the transistors of the sevent...
by loki
Tue Oct 27, 2020 6:34 pm
Forum: Music Tech DIY
Topic: LinnDrum LM-2 clone in progress
Replies: 24
Views: 1465

Re: LinnDrum LM-2 clone in progress

What do you think, is this AM6070DC fake? https://www.ebay.com/itm/AMD-AM6070DC-DIP-18-Companding-D-to-A-Converter-for/222395449416?hash=item33c7cd4048:g:uiUAAOSwEppUPQJa The ceramic package is appropriate for the time period of the date code: 16th week of 1984. I think you might buy the DAC88 and ...
by loki
Tue Oct 27, 2020 6:08 pm
Forum: Music Tech DIY
Topic: LinnDrum LM-2 clone in progress
Replies: 24
Views: 1465

Re: LinnDrum LM-2 clone in progress

This one? https://www.ebay.com/itm/PMI-DAC88EX-8-BIT-D-A-Converter-CDIP18-X-1PC/152180743320?hash=item236eaddc98:g:xRIAAOSwENxXlhkn That is labeled right but it looks different than the ones I have. I know mine are authentic, I bought them from an authorized distributor back when they were current ...
by loki
Tue Oct 27, 2020 12:58 pm
Forum: Music Tech DIY
Topic: LinnDrum LM-2 clone in progress
Replies: 24
Views: 1465

Re: LinnDrum LM-2 clone in progress

PMI made an equivalent part, the DAC88. Good luck finding any.
by loki
Mon Oct 26, 2020 4:47 pm
Forum: Music Tech DIY
Topic: LinnDrum LM-2 clone in progress
Replies: 24
Views: 1465

Re: LinnDrum LM-2 clone in progress

Hate to be pedantic but: there is the LM-1, the LinnDrum and the Linn 9000. Roger Linn himself points out that there isn't any such thing as an LM-2. When it comes to the parts used on the CPU board, almost all of them are still available (in one form or another). Due to a lack of advanced electrica...
by loki
Sun Oct 04, 2020 12:54 pm
Forum: Music Tech DIY
Topic: Noise Transistor “Selection”
Replies: 16
Views: 457

Re: Noise Transistor “Selection”

Better to use a Zener diode somewhere in the 10 to 12 volt range. See this Maxim applications note for an example.
by loki
Thu Sep 24, 2020 3:34 pm
Forum: Music Tech DIY
Topic: electronotes/musical engineer's handbook/pcc pdfs
Replies: 145
Views: 16098

Re: electronotes/musical engineer's handbook/pcc pdfs

EDIT: joking aside, is the concern vis-a-vis copyright that contributors will bar the redistribution of their contributions? Unless they're being paid royalties (which, given they aren't for sale, seems unlikely), why would they? Seems like it wouldn't be much of a risk to assume they won't and in ...
by loki
Sat Jul 25, 2020 8:42 pm
Forum: Music Tech DIY
Topic: ARP 1047 SVF
Replies: 10
Views: 708

Re: ARP 1047 SVF

One of the first publications of a SVF design is IEEE 1968 Vol 56 pp 1137-1139 by J. Tow of Bell Labs. While not a complete analysis, it does have brief discussion of the sensitivity of the system. I collected quite a few discussions on SVF analysis, including ElectroNotes. I have yet to see any di...
by loki
Fri Jul 24, 2020 5:46 pm
Forum: Music Tech DIY
Topic: ARP 1047 SVF
Replies: 10
Views: 708

Re: ARP 1047 SVF

For those interested, Dennis Colin's patent is: 3805091
by loki
Wed Jul 22, 2020 11:30 am
Forum: Music Tech DIY
Topic: ARP 1047 SVF
Replies: 10
Views: 708

Re: ARP 1047 SVF

Using an OPA2134 or OPA1678 is superior to the dual FET and LM301. You are correct that there were no FET input op-amps when the 1047 was designed. The configuration Dave Rossum used a few years later in the UAF is an improvement over the 1047. He used the FET in a source follower configuration and ...
by loki
Sat Jul 18, 2020 10:34 pm
Forum: Music Tech DIY
Topic: Cd4017 Clock
Replies: 9
Views: 340

Re: Cd4017 Clock

In the TI data sheet, (schs027c) on page 3, the input voltage is specified at three different power supply voltages. The data sheet is your friend. Do it, and yourself, the favor of learning to understand the values that are specified and what they mean for your circuits.
by loki
Fri Jul 10, 2020 7:22 pm
Forum: Music Tech DIY
Topic: Attenuverter Comparison
Replies: 5
Views: 258

Re: Attenuverter Comparison

The source of the simple version!
by loki
Sun Jul 05, 2020 7:04 pm
Forum: Music Tech DIY
Topic: Lost in BJTs
Replies: 20
Views: 924

Re: Lost in BJTs

A couple of more titles to add to the reading list. The GE Transistor Manual (I have edition 7, 1964), the Motorola High-speed Switching Transistor Handbook (1963, I have the 9th printing from 1975), and Albert Malvino's Transistor Circuit Approximations, which after the third edition became Semicon...
by loki
Tue Jun 30, 2020 2:31 pm
Forum: Music Tech DIY
Topic: electronotes/musical engineer's handbook/pcc pdfs
Replies: 145
Views: 16098

Re: electronotes/musical engineer's handbook/pcc pdfs

Hey all, I just got my copies of MEH, BG-PCC, and a lot of other electronotes. I'm glad you've found a solution for your own needs. I pulled my boxed issues of Electronotes off the shelf. The early issues were typed single spaced and then mimeographed. I hate to think about reading a PDF of scans. ...
by loki
Fri Jun 26, 2020 12:25 pm
Forum: Music Tech DIY
Topic: Lost in BJTs
Replies: 20
Views: 924

Re: Lost in BJTs

Download the: National Semiconductor - Discrete Databook 1978 and the 1982 National Transistors Databook. You can find them at the internet archive and many other places. There is also the: National Semiconductor Fet Databook 1977 They contain descriptions of the processes used for their entire line...
by loki
Fri Jun 26, 2020 12:09 pm
Forum: Music Tech DIY
Topic: electronotes/musical engineer's handbook/pcc pdfs
Replies: 145
Views: 16098

Re: electronotes/musical engineer's handbook/pcc pdfs

I'm puzzled that some of you persist in the notion that Electronotes, MEH, and PCC has some economic value. It has some cultural value because it documents the early stages of the Synth DIY movement. If Bernie donated his materials to a University they would lie in storage, at best, because it takes...
by loki
Wed Jun 24, 2020 12:45 pm
Forum: Music Tech DIY
Topic: Something New from Doc Sketchy
Replies: 679
Views: 51771

Re: Something New from Doc Sketchy

I want a 4U board set. One question, I have a 100 pieces of the SSI2164 and no SSM2164s. How awkward will it be for me to use them. I'm assuming you are still using SSM2164s.
by loki
Sun Jun 14, 2020 12:52 pm
Forum: Music Tech DIY
Topic: R.I.P. LM3046: byebye affordable temp stabilized VCO's
Replies: 53
Views: 6467

Re: Re:

What about the ceramic DIP package versions of the 3046? Any advantages over the plastic DIPs? Rick The characteristics of the transistors are more important than the thermal characteristics of the package. The transistors in the LM3046 are lame compared to modern devices. Read the SSI2164 data she...
by loki
Tue Jun 09, 2020 6:51 pm
Forum: Music Tech DIY
Topic: electronotes/musical engineer's handbook/pcc pdfs
Replies: 145
Views: 16098

Re: electronotes/musical engineer's handbook/pcc pdfs

The suggestion from loki in this thread that people who contributed ideas also own a copyright to Electronotes is not how copyright works; copyright applies to the words, not the ideas. I didn't suggest that people contributed ideas, I stated and know that people contributed written material that B...
by loki
Tue Jun 09, 2020 12:38 pm
Forum: Music Tech DIY
Topic: electronotes/musical engineer's handbook/pcc pdfs
Replies: 145
Views: 16098

Re: electronotes/musical engineer's handbook/pcc pdfs

...with electronotes there was a real financial incentive to produce the magazine. As someone who subscribed from the early days on, no, Bernie did it as a labor of love. He was lucky to break even! I entirely understand his frustration and reluctance to sink more time and money into something that...
by loki
Tue May 05, 2020 1:46 pm
Forum: Music Tech DIY
Topic: Shaping Capacitor Discharge Curve - Envelope
Replies: 8
Views: 360

Re: Shaping Capacitor Discharge Curve - Envelope

Generate two different discharge curves and sum them together.
by loki
Mon Feb 17, 2020 3:48 pm
Forum: Music Tech DIY
Topic: Measuring Rbulk of transistors
Replies: 91
Views: 4828

Re: Measuring Rbulk of transistors

A couple of times in the past I have posted suggesting the use of the MMDT4401 (NPN) and MMDT4403 (PNP) as exponential pairs. The late Marshall Leach recommended the 2N4401 and the 2N4403 as the secret sauce in many high end audio designs. Because of their higher current rating they have a bigger ba...
by loki
Thu Nov 28, 2019 8:33 pm
Forum: Music Tech DIY
Topic: 3Peak Opamps
Replies: 25
Views: 1319

They usually do this by using the services of a company based in Singapore who take an IC and slice it layer by layer and produce a new set of masks. So whilst not a perfect copy, they are usually pretty close. I expect the 3PEAK device mentioned was produced in this manner from the original 2604. ...
by loki
Fri Nov 01, 2019 7:45 pm
Forum: Music Tech DIY
Topic: Testing CA3080s
Replies: 6
Views: 1220

Thanks for the information. Is it really necessary to produce your circuit to verify the fact that opamp is not counterfeit ? Or it's enough to use Elektor example ? Depends what you are using the CA3080s for. The Elektor circuit allows you to match parts by transconductance. My circuit lets you se...

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