[2780] Pre-Assembled Module Stock

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

Some of the pre-assembled modules are not in stock because of supply chain issues and delays. The parts for the Dual Opamp module and the Mini-Booster are showing 31 week delivery time – more than 6 months!

Not only that, the manufacturer has raised the price yet again, as well as the minimum order quantity, and I am afraid that they will be too expensive to restock. It costs thousands of dollars to purchase stock for just one type of module.

To this point I have always had the modules built in the USA, but it looks like I am going to have to find an assembler outside the US if I plan on keeping the modules in stock.

The good news is that there are plenty of the Mosfet Booster modules in stock since I bought several hundred just before the pandemic started.


[2777] Microprocessors in Stock

Date: June 8th, 2021 | Comments : none | Categories: DIY.

I managed to purchase a couple of tubes of the microprocessor used in the DPDT relay switch, so it is available to order again.

I just read a news article that said that many semiconductor shortages will continue into next year. I hope the projection is wrong!


[2773] High Gain Booster

Date: May 12th, 2021 | Comments : [2] | Categories: DIY.

[2771] New Pedal Day!

Date: May 7th, 2021 | Comments : none | Categories: DIY.

New pedal day! Robert Keeley generously sent me a pair of his latest pedals.


[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.



AMZ Home Page

Guitar FX PCBs