[2766] Null Testing Op Amps

Date: April 19th, 2021 | Comments : none | Categories: DIY.

If you are interested in reading about the process of conducting the op amp comparisons that I wrote about recently, I have posted a brief article describing the test circuit and what I plan as the next step.

Op Amp Null Tester


[2733] International Mail Is Back

Date: April 1st, 2021 | Comments : [1] | Categories: DIY.

International First Class Mail has been reinstated by the USPS. I can ship international orders again at a rate close to the previous charge. is mostly dead. I can still send a Priority Envelope for $40 to $41 depending on the destination, but First Class mail of merchandise is no longer accepted for international shipping. I cannot even make a customs form for it using the USPS web site.

Sales to US addresses remains much the same with only a small postage increase. International ordering is open.


[2755] Op Amp Comparisons

Date: March 13th, 2021 | Comments : none | Categories: DIY.

I designed and built a null tester to try to determine if I could detect a difference in op amp chips. You can see the results in the AMZ Lab Notebook.


[2750] LM4562 Problems

Date: March 5th, 2021 | Comments : none | Categories: DIY.

I have posted before about problems that I encountered when using the LM4562 low distortion op amps, including most recently in the LM358 article in the Lab Notebook.

Just today, I stumbled across what may be the answer to the issue with that chip. It seems that the high value input resistor is not supplying enough bias current at startup and the chip latches. I have not tested this by lowering the value of the resistor, but I plan on putting the direct box pedal back on the bench to see what I can find.


[2738] Blank Tab Books

Date: February 25th, 2021 | Comments : none | Categories: DIY.
My new blank tab notebooks are now available on Amazon. Check them out at:

Guitar Tablature Notebook

Bass Tablature Notebook

Factoid: The cover of the guitar book is an actual scan of the back panel of my tweed Deluxe amplifier. The books turned out really nice and I hope that you enjoy using them.

Thanks for your support!


[2737] LM358 for Audio

Date: February 20th, 2021 | Comments : [1] | Categories: DIY.

I wrote a short article about using the LM358 for audio. It is in the Lab Notebook.


[2743] 30 Days To A Better Novel

Date: January 29th, 2021 | Comments : none | Categories: DIY.

With Kindle Unlimited, you can read my latest book for FREE!

New opportunites and online retail sites make this the best time ever to be an author. It is easier today than ever before to get published, and you should take advantage of the available opportunities!

With “30 Days To A Better Novel”, you can improve your novel writing, your book’s plot, and the character development. This book has one lesson per day for you to use to evaluate the finer points of novel writing, and how to apply them to your book.

Click here to see it on Amazon.


[2731] FV-1 Bank Switching Again

Date: January 11th, 2021 | Comments : [2] | Categories: DIY.

In a previous post, I showed how to use an SPDT switch to select between multiple memory chips on the Spin FV-1 to expand the number of patches available. In this post, I will show how to use a single DPDT switch to allow access to two memory chips plus the internal sounds that are built into the FV-1.

The extra set of poles on the switch allows the internal patches to be enabled when needed or disabled when the external memory chips are active. The switch needs to be a center-off DPDT, which is commonly available.

The middle pin of the left set of switch poles has a pull-down resistor and is connected to pin 13 of the FV-1. There are no other resistors or connections to pin 13. When the switch is in the middle position, the new resistor pulls pin 13 to ground to enable the internal sounds, and the other set of poles has disabled both external memories.

When the DPDT is toggled to either end position, pin 13 is made HIGH and the external memory chips are enabled as in the previous article.

This alternate bank switching method allows access to internal and external sounds with a single switch.



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