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Great Gift Idea

I received this in an email from American Microsemiconductor the other day. I had to share this because I know you're in the market for a 500A Dual Thyristor Module. Aren't we all? Perhaps if they offered it in 600 Amps I would put it on my wish list. Oh well, maybe next year.

Thanks for reading,


Nixie Tube Clock by Dalibor Farný at Tube Depot

The Art of Making Nixie Tubes:

I came across this video while searching for Compactron tubes at Tube Depot.  This is awesome! New production Nixie Tubes!

These modern Nixie tubes are now part of a custom clock called "BLUB KEO" available at Tube Depot.  It looks like Blub Keo began as a KickStarter project at

Click the image above for the Kickstarter video or use the link below.
The kickstarter video link:

BLUB KEO - Color Options

New Production Nixie Tubes 

Nixie Clock - Copper Color

The single digit cycles through the numbers for the hour and minutes. It's pretty cool.


  • Time
  • Date
  • Temperature
  • Alarm
  • Zero Noise
  • Zero Heat
  • USB power connection 
  • Infra red remote
Blub Keo is about the size of a soda can and sells for about $450.00.
For more information see Tube

Thanks for reading,


Gallien-Krueger 400RB Repair with Deoxit Fader Lube

My bass player still owns the same Gallien-Krueger 400RB bass amp he used back when we both lived in Los Angeles in 1989. It had been a while since he had used it last so it didn't work when he powered it on. The power came on, but with no sound at the output.

Everything looked good inside. It was super clean. But, the pots were very hard to turn. I suspected that the old pot grease had hardened and was getting between the wiper contact and the carbon element so I decided to clean all of the pots with Deoxit Fader Lube.

This stuff is amazing. It works so much better than the old can of Shack tuner cleaner I used in the past. A simple spray inside the element and shaft and then rotate back and forth a few times. Repeat the process until they feel new again.

When repairing any electronic equipment make sure to pay attention to what parts will have voltage potentials on them. Notice the two TO3 transistors at the upper right of the next image.

They are part of the power amplifier circuit. One transistor has about +65VDC on it. The other about -65VDC.  Let me tell you that +65V and -65V do not add up to 0V. Across those transistors is about 130VDC of silent killing potential. We must be very careful and respectful when working on electronic equipment.

Thanks for reading,


Universal Audio M610 Tube Preamp

Inside The Universal Audio M610 Vacuum Tube Preamp

The M610 preamp is the same tube preamp used in the LA610,  LA610 MKII and 2-610. The preamp is made up of two separate feedback gain stages that are cascaded one after another.

The UA M610 Circuit

The first feedback gain stage can be adjusted with the "GAIN" switch on the upper left of the front panel. This switch selects a feedback resistor that can add or subtract gain to the circuit. The first tube in the circuit (left tube) is a 12AX7 dual triode.

The following feedback gain stage uses a 6072 (right tube). The 6072 is similar to the 12AT7 dual triode. Notice that the big knob says "LEVEL". This is because it acts like a volume knob and not a gain knob in the circuit.

The first feedback gain stage feeds the 250k ohm "LEVEL" potentiometer and you adjust the input level to the following 6072 feedback gain stage.

More info and measurements coming soon.
Thanks for reading,


12AX7 Vacuum Tube Breadboard Adapters On Ebay


These are now available on Ebay at this link: BB-NOVAL Breadboard Adapters

They also work with other tubes such as 12AU7, 12AT7 and the EF86 Pentode.  You can learn how to design your own 12AU7 gain stage by reading my white paper 12AU7 Gain Stage Example.

Thanks for reading,

12AX7 Vacuum Tube Breadboard Adapter On Ebay


These are now back on Ebay at this link: BBX7 Breadboard Adapter.

Find out how to design your own 12AX7 Gain Stage by reading my white paper "12AX7 GAIN STAGE EXAMPLE on my website at .

If you have any questions you can comment here or contact me via my web page.
Thanks for reading,


How To Build A 12AX7 Gain Stage Part 4 (Measurements)

Part 4 of my video series on How To Build A 12AX7 Gain Stage. This video covers DC measurements, AC gain measurements, and frequency response measurements. SPICE simulation is then compared to the real-world tube circuit.

Thanks for watching,