[2470] Fake LM308

Date: December 13th, 2018 | Comments : [2] | Categories: DIY.
LM308-fake

Fake LM308 in a Mooer pedal… well, not an original National Semiconductor chip anyway.

So, is it a fake if you mark a plain cheap op-amp that meets or exceeds the specs of the original LM308 with that part number but the internal circuit is not the same?

It will work in circuits designed for the LM308 and perform well. It does the job. But at the fringes and limits of the electrical characteristics where many fx pedals operate, it will not be the same as an IC with the internal circuit design of a real original NatSemi LM308. Is that a fake or just a poor substitute?

 

[2459] Hackspace magazine

Date: November 30th, 2018 | Comments : [1] | Categories: DIY.

A great resource about building stuff, including electronic projects, HackSpace magazine is packed with projects for fixers and tinkerers of all abilities.

You can get FREE issues at:

https://hackspace.raspberrypi.org/issues

Enjoy!

 

[2449] The Business of Making Pedals

Date: November 29th, 2018 | Comments : [1] | Categories: DIY.

Why are US-made pedals significantly more expensive than Chinese clones?

TL;DR: Chinese companies receive subsidies from China’s central and provincial governments. They also have an artificially low currency-exchange-rate, smaller profit margins, few worker safety programs, little environmental control, low taxes, low wages, long hours and few worker benefits, so the price of Chinese products will always be lower than similar products made in the USA.

(more…)

 

[2435] Hum, Whine and Noise

Date: October 10th, 2018 | Comments : none | Categories: DIY.

I often see people post that their pedal is making a noise, but they fail to describe the sound adequately to allow anyone to decipher the cause. For example, a hum is low pitched and is often caused by a poor ground connection or bad cables. A hum sounds like this (you may need to turn down the volume):

A noise caused by power supply aliasing, as from a poorly designed charge pump, or from radio frequency interference will be higher in pitch and often sounds like this:

Another common noise is a random background hiss. All electronic components generate a very small noise voltage and high gain circuits can make the sound much more prominent, like this:

Recognizing the type of noise your pedal is producing is the first step to working out a solution to the problem!

 

[2419] PT2399 Analysis

Date: July 30th, 2018 | Comments : [1] | Categories: DIY.

PT2399 delay chip

ElectroSmash has published a thorough analysis of the PT2399 delay chip, which has been used in many echo and delay stompboxes.

For those who would like a copy to keep on hand when working offline, I have converted the article to PDF format and it is available for free download here.

Enjoy!

 

[2423] Metro Songs Podcast with Janglebox

Date: July 26th, 2018 | Comments : none | Categories: DIY.

Steve Lasko, creator of Janglebox, is interviewed on the Metro Songs Podcast episode 5. It’s an interesting talk with plenty of behind-the-scenes info.

Near the end, Steve even lets the cat out of the bag that I designed the J-Gate pedal for him. Smiley

Check it out!

 

[2414] New Tariffs on Components

Date: June 21st, 2018 | Comments : [1] | Categories: DIY.

Bunnie Huang says that new tariffs coming July 6th will hurt educators and makers, and encourage offshoring.

“It taxes the import of basic components, tools and sub-assemblies, while giving fully assembled goods a free pass.”

New US Tariffs are Anti-Maker and Will Encourage Offshoring

 

[2400] Op Amp Circuit Collection

Date: April 26th, 2018 | Comments : [2] | Categories: DIY.

Every op amp circuit you’ll ever need (almost):

Texas Instruments AN-31 by Bob Pease

 

[2386] Booster Gain

Date: April 4th, 2018 | Comments : [2] | Categories: DIY.

I see posts occasionally asking which booster pedal has the most gain.

The available gain of a booster by itself tells you very little. Two additional deciding factors are: How large is the input signal, and what is the max voltage swing of the booster output?

Each circuit has a maximum voltage swing and when that is exceeded, distortion will result. In a standard circuit powered with 9v, the max output voltage swing is probably 7v or so (+/- 3.5v). Therefore, if your pedal has 20dB (10x) of boost, then the maximum input before distortion is 0.7v peak-peak (7v/10). Any more gain will distort. Any signal larger than 0.7v pk-pk will distort. Most guitar pickups exceed 1.0v pk-pk on the initial string pluck.

If you pedal has 35dB of boost, that is a voltage gain of 56x. So the maximum input signal before distortion is 7v/56 or 0.125v pk-pk. Not much headroom.

You don’t need more gain if you want a boosted clean signal. You need (want) more headroom, and the easiest way to do that with a booster pedal is to power it with a higher voltage, such as 18v or 24v, to give a larger output voltage swing before distortion.

More reading: Boosters, Gain and Distortion

 

[2378] Amazon package day

Date: March 8th, 2018 | Comments : [1] | Categories: DIY.

EEVblog meter

 


 

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