Posted on Tuesday, 20th December 2011 by Auw Jimmy

Finding a good soldering iron is not an easy job. But once you find it, it will simplify the rest of your life – I mean, the rest of your soldering life

One of my preference brand is Goot from Taiyo Electric, Japan. Although there are several affordable and also durable brand, but I think I’m quite OK with this Goot soldering iron (but remember, this is not the only brand in the world and the important is the man behind the gun, I mean, the solder).

I’m quite happy with CS-30 series which I bought maybe more than 7 years ago. It’s very durable. The main reason for me to change is the screw to remove the tip has broken (so I can’t change the broken tip). The new replacement is CS-31 which carries similar spec (25W version).

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Tags: Goot, Melting Temperature, solder, Soldering Iron, WBT
Posted in Collectible Stuff, DIY Audio, Measurement | Comments (6)

Posted on Tuesday, 16th August 2011 by Auw Jimmy

Some people send me an email asking about how to measure cathode current and resistor rating. I will show you how to do it and actually this way is not only applicable for cathode resistor (but commonly used for that purpose).

Basically, there is 2 common way to do it. First, put you Ampere meter in series with the resistor. Second, is to measure the voltage on the resistor, then calculate the current based on the Voltage, Current, and Resistance formula (which V=I*R).

For the sake of simplicity, we can opt to use the second method. We cut the shrink from the resistor pins and put the probes there.

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Tags: bias, cathode resistor, Sanwa
Posted in DIY Audio, Measurement | Comments (0)

Posted on Tuesday, 16th August 2011 by Auw Jimmy

Sometime I’m curious how hot your tube is? Well, this short experiment will give you some idea. Different tube may have different thermal characteristic (simple logic: the higher current on the filament, expect higher temperature).

Off course we can use probe to measure the surface temperature. But I’m thinking another approach. So I get myself an infrared thermometer to examine the temperature in more detail. As example, I use Russia 5U4 Rectifier tube, rated at around 2A filament.

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Tags: 5U4, infrared thermometer, rectifier, tube temperature
Posted in DIY Audio, Measurement | Comments (1)

Posted on Sunday, 7th November 2010 by Auw Jimmy

I used to like “hook-type” probe used in oscilloscope , as this type is very convenient in testing small parts. You just hook the test clip and see the result in the display. But why most multitester (Digital or Analog) uses standard probe? I don’t really got the idea.

So, let’s build by ourselves the oscilloscope-like probe for our multitester (you can call multimeter, DMM, or whatever).

You will need 3 major parts:

• The connector head (to plug into your multitester)
• Cables (AWG 18 or bigger, prefer insulated to cover at last 300V)
• The “hook-type” (you can also call it spring clip type) probe

The minor parts needed:

• Soldering iron and other soldering tools
• Hairdryer or matches
• Time (few hours)
• Motivation (yeah!)
• etc

Ok, first, put the cable on the connector head. Mine has screw to lock, but I put extra solder to make sure it will tight there forever and ever. See, they will be there, won’t release even you pull it hard.

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Tags: multitester, spring clip probe
Posted in DIY Audio, Measurement | Comments (1)

Posted on Monday, 1st November 2010 by Auw Jimmy

In the middle of the night, after finishing my tube rectifier dual socket modification, I prepare some tube rectifier to test the new socket. I think it’s gonna be nice to evaluate the sonic of some rectifiers to

Actually, I have known the winner, although I haven’t compared them one by one on same setup – like this time.

Let’s start with Telefunken RGN 1054 Mesh, the basic or entry level tube rectifier from Telefunken. With the price around US$ 100 or less, this tube is just fine to let you know the special of RGN families. It sounds musical, crisp, and detail. The vocal is nice, although slightly thin. The Mesh Anode version is better in terms of transparency and musicality than the Solid Anode one.

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Tags: rectifier, RGN, Telefunken, Valvo
Posted in DIY Audio, Measurement | Comments (20)

Posted on Sunday, 19th September 2010 by Auw Jimmy

I’m thinking to create a first gift for my newborn (ooopsss… he is not yet here, just about to). A small MP3 Player with tiny amplifier to drive a small speaker should be a nice idea. I will introduce him to music as early as I can. So this could be the right time.

After searching around, I finally find a small chip amplifier, TBA820. It’s a small, 8-pins DIP type, low power at 2 Watt maximum on B-Class. Not a bad as a start. I don’t play with A or AB-Class due to heat issue. The goal is small design, almost no heat, and could be powered with battery when needed. This TBA820 chip amp should be excellent stuff.

The finished kit shown as below. With around 5 VDC power from battery, it could drive my tiny 2″ mini speaker at quite loud volume. Nice!

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Tags: Amplifier, oscilloscope, TBA820, Tiny Amplifier
Posted in DIY Audio, Measurement, Personal | Comments (5)

Posted on Sunday, 8th August 2010 by Auw Jimmy

I was playing with my Rigol Oscilloscope to measure my laptop power output. The sound card was Realtek ALC660.

I played a 1 kHz sine wave with a software and measure the output. Since this was not an isolated environment (I have some application running on the background), so the frequency measured was not completely locked at 1 kHz.

On my typical daily usage, the output measured at 102 mV.

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Tags: ALC, measurement, oscilloscope, Realtek, Rigol
Posted in DIY Audio, Measurement | Comments (4)