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Banish Tarnish With the PrepPen

And check out this unique microphone isolation solution

Albuquerque engineer Lew Wallach writes about the PrepPen, a shirt-pocket-sized surface cleaner that uses glass fibers to remove surface corrosion and oxidation without removing the base material.

The PrepPen was designed for auto body shops needing to spot-sand a vehicle or for chipped paint repairs, but the PrepPen is also perfect for cleaning component leads or wire before soldering. The glass fibers break off into a fine dust when it is used, but in the process, the fibers remove oxidation.

Fig. 1: The PrepPen does a quick job on corrosion.

Fig. 2: Tarnish on this coin disappears after using the PrepPen.

To use it, put the item to be cleaned on a paper towel or a sheet of paper. When finished, wipe the surface with a paper towel and wash your hands.

Fig. 1 shows Lew using the PrepPen on a 1/8 W resistor and a piece of copper wire. Fig. 2 shows how the PrepPen removed tarnish from a coin.

Lew could not find them at chain car part stores, although auto body shops use them. He finally ordered them online from Enter “PMC3437” in the keyword search.

The PrepPen is manufactured by Pro Motorcar. At under $5 it won’t break the budget, and Lew suggests ordering refills, as the PrepPen will probably get a lot of use. He keeps one on the bench, one in the toolkit and one in the home shop. They also make a great giveaway for friends.

A few years ago, Lew was working for NASA. He attended a high-reliability hand soldering course. And 80 hours later, Lew knew how to solder! In the course, they used the pencil-type typing erasers for soldering prep — remember them?


If you search the web for information on Cramolin, an amazing contact cleaner and restorative sold in the 1970s and ’80s, you’ll find the product is no longer available in the U.S. Urban legend has it that the product did not meet EPA regulations and was discontinued.

Caig Laboratories replaced the product with DeoxIT, readily available stateside.

Fig. 3: Stabilant 22 is a liquid contact cleaner.

Alternatively, I recently received a sample of Stabilant 22 from American Recorder. This chemical contact cleaner is available through distributor Broadcasters General Store.

Stabilant 22 is an electric contact enhancer that meets both EPA and the Canadian WHMIS environmental regulations. A photo of the sample, complete with an application brush, is seen in Fig. 3.


Fig. 4: Tom Weber’s LNB voltage measuring device.

Indianapolis WISH(TV) Channel 8 engineer Tom Weber put together a pocket-sized LNB voltage meter in a miniature plastic box. Adding a female F connector, LNB voltage can be quickly verified.

Tom’s finished instrument is pocket-sized and shown in Fig. 4.


We’ve all heard of building an emergency studio in a closet.

With that in mind, the acoustical treatment folks at Auralex Acoustics came up with a novel product.

Fig. 5: Auralex Acoustics MudGuard v2 provides microphone isolation.

Senior Sales Engineer John Lynch of distributor Broadcast Supply Worldwide demonstrates the MudGuard v2 in Fig. 5. It’s a unique microphone isolation solution. The proprietary convex design diverts internal shell reflections, offering improved microphone performance. Flat or concave shields focus energy toward the microphone.

John says this MudGuard v2 is ideal for podcasting studios.

Planning a studio overhaul? John recommends “Acoustics 101: Practical Guidelines for Constructing Accurate Acoustical Spaces.” Open or download this 52-page PDF by clicking on the “Acoustics 101” link in the top banner ribbon of the Auralex website.

Your tips toWorkbench will help fellow engineers and qualify for SBE recertification credit. Send your ideas to [email protected]. Fax to (603) 472-4944.

Author John Bisset handles West Coast sales for the Telos Alliance. He is SBE certified and is a past recipient of the SBE’s Educator of the Year Award.