Entries Tagged 'Toys' ↓

300 Ohm TV feedline

It used to be that every TV antenna used a 300 ohm feedline. It was 300 ohm twin lead. It was cheap and the lowest loss feedline you could get. The only problem it had was that it picked up noise. In an analog system noise shows up on the screen. To get rid of noise TV feedlines were changed to coaxial feed lines. These were shielded and pretty much eliminated noise.

Digital TV does not show noise on the screen. All it needs is a minumum signal level. Once that signal level is met you get a perfect picture. No noise, no ghosts, no aberrations, just a perfect picture.

So now I am going back to 300 ohm twinlead and dumping the coax. Less loss in signal from the antenna using 300 ohm twinlead and it is much less expensive too.

The Game of Life

I read somewhere that in the game of life the person with the most toys at the time of death wins the game.

I believe that is a very short sighted outlook. My definition of a winning position is to be the one with the most toys that are still working when the end comes.

Recently one of my ‘toys’ broke. Several years ago I became the owner of a lawnmower that propelled itself. You did not need to push it. Just guide it and let it pull you along.

At the start of this season it required pushing. Lots of pushing. After half an hour of pushing I was all pushed out. This thing needed to be repaired or replace.

Replace was out of the question. New lawnmowers are now priced at what I would consider reasonable for a good used car. Guess I am still living in the 60′s. That is the 1960′s.

Repair was going to require parts. The main problem was that the drive bushing on the vertical shaft run by a pulley and belt from the main engine shaft was worn out. That and the fact that the worm drive gears were caked full with hardened grease was what was keeping the drive from driving.

Cleaning the gears was not all that much of a problem. Finding parts was another story. There are lots of places on the internet that offer parts for lawnmowers of all kinds including the one I have. All those places are completely worthless. Prices are outreagous, shipping is unreasonable, parts selection is non-existent. After cruising the internet for half an hour I was pretty well certain that I would not be able to find the part I needed.

Well, it turns out that I did not need to buy a new part after all. The drive gears are housed in a casting that bolts together. The casting is in two parts, upper and lower. The shaft that drives the wheels runs horizontally. The shaft that drives the horizontal shaft runs vertically. The two shafts combine in the casting and are supported by bushings. Two bushings for the horizontal shaft and one for the vertical shaft. The three bushings are identical! So, the horizontal shaft was polished so that one of the still good bushings could be removed. The good bushing was used to support the vertical shaft. The worn out bushing from the vertical shaft was used to support one side of the horizontal shaft. A worn out bushing on the horizontal shaft did not seem to bother the function of the shaft.

After a few choice words a few beers in celebration and a sharpening of the blade, I am again in business with a functioning lawn mower. It cuts, it mulches, and I don’t have to push it.

Tube Amp

This tube amp is something suitable for use as a small computer speaker amp. Inspired by the recent discovery of the Morgan amp.

The Morgan amp is a simple three tube single channel amp using old AC/DC 5 tube radio parts.

A 50L6 output, 35Z5 rectifier, and 12SQ7 pre-amp all cobbled together to give at least an honest 1 watt of audio to a pair of simple speakers.

Cheep, cheap, inexpensive. The Morgan amp runs directly off the 120vac line. Not a safe application, but it can be made safe by using an isolation transformer, fuse, and on/off switch.

The low cost is a direct result of the simple design.

I did not have but one 35Z5 but I did discover a few 12AV6s, 50C5s, and 35W4′s. These are the miniature equivalents to the tubes used in the Morgan amp. So I decided to use them in an updated Morgan design. The only change was to replace the tubes with the ones I had on hand.

Folk who do not have a box of parts to pick from can still build this amp. The most economical approach is to find two AC/DC radios at a thrift shop or garage sale. Working or not, these radios can provide all the parts necessary to build a two channel Morgan amp. Three of the tubes in these old 5-tube AC/DC radios are used in this amp. One of the remaining tubes is an IF amplifier and the other is a mixer.

It could be argued that this amp driven by a crystal radio can provide far better fidelity reception of AM signals than the original radio. Instead of a superheterodyne style radio we revert back to a simple detector and audio amplifier. We might loose a little in selectivity and sensitivity but I doubt anyone listening to powerful local stations would notice anything but the lack of interference, noise, and squeals with the mixer gone. (Wonder why these things are called SUPERheterodynes? Most things I see with the ‘super’ label, are anything but super.)

In my design I used the goofy printed circuit mounted tube sockets found in the AC/DC radio I had. I simply cut them out of the old printed circuit board and mounted them with screws to a scrap of unused printed circuit board I had been saving. Somewhat more work than it should have been but very effective.

The housing for the amp was made from scrap pieces of redwood that had been salvaged from a demolished redwood deck. The complete enclosure is redwood and plexiglass. The plexiglass is also of the salvaged variety.

The end result is lots of noise for little cost. Actually no cost except for the time to build the thing.

You might well wonder ‘why do this’. Okay, you can buy new amplified computer speakers for under
ten dollars but then they are ten dollar amplified computer speakers. They don’t have the characteristic sound of a tube amp.

What characteristic sound? The sound of rock and roll.

All this started when tubes were cheap and amps were popular. Folk were not too concerned about how linear the sound was. Or how well a full spectrum of sound frequencies were replicated. All they wanted was something to make noise. Meanwhile, tube amp designers were not all that concerned about building expensive stuff with super good specifications. Why bother when it cost much less to build something that just made a lot of noise. Besides this is what was selling. No future in building stuff no one would buy. It was much easier to sell a cheap tube amp than a more expensive carefully engineered amp. The rock and roll crowd picked up on the cheap amps and used them. Their cheap and distorted audio gave the music a distinct flavor and rock and roll was born.

Now days real rockers can appreciate the sounds of that distinctive distortion that you can only find in music coming from a poorly designed tube amp.

So here you have it, a poorly designed tube amp for the rock and rollers.

You don’t have to dream about it. You can actually re-live the past. At least listen to the music of the past on real tube equipment.

When you can do it for no cost, why not?

Cedar Desk Lamp with Dimmer

Two years ago I began building ‘STUFF’ out of cedar. I found that I could buy an eight foot, rough cedar, 2X4 post at Home Depot for about $5.50.

Once I got the thing home I would cut it up on the table saw into 2 inch by one inch 8 foot sections. I trimmed off the rough sides, cut out any knots and imperfections, glued some of the pieces together to make 2X2 inch posts or six inch square sections 2 inches thick or any other size that came to mind.

I liked the way plain varnish darkened the cedar and brought out the beauty of the wood without need for stain.

I began building floor lamps and desk lamps. Each made from 100 percent cedar, even the shades. Those very thin trimmed rough sections ended up making perfectly good lamp shade material.

Recently I came into possession of a small table lamp that was a touch on, touch again to make brighter, touch a third time to make brightest, and touch again to turn off. It soon became one of my favorite lamps until recently the touch mechanism quit working. Touch it as you may it remains on bright. After I could not get the base appart, I gave up on this six dollar thrift shop item.

I retired it to temporary spare computer service. The shade attaches to its light bulb with a wire hoop. I turn the hoop clockwise, seating the bulb to turn it one. Turn it counterclockwise, unseating the bulb to turn it off. It never had a real on/off switch. Just the high tech touch on/bright/off function that quit working. Now it has a really low tech but effective way of turning it on and off. Very primitive but not as bad as unplugging it and plugging it back in.

Now I needed a replacement.

Several months ago we replaced eight 100watt ceiling mounted wall washer spots with compact flourescents.
The first thing we noticed was the new compact flourescents do not work well with incandescent dimmers. The dimmers were replaced with ordinary switches.

Not wishing to discard perfectly good incandescent dimmers, I decided to use one to invent an new desk lamp. One that had a dimmer feature.

I used my fostener bit assortment to hollow out the base of one of the desk lamps. Then I mounted the dimmer inside the hollowed out recess and glued it in with hot melt glue. Got it wired up and presto, a nice incandescent desk lamp with dimmer.

Works great and is a near perfect replacement for that touch lamp that failed.

Train Table

Ah, toy trains. I remember my first toy train. It did not need a table. The three rail metal track was layed out on the floor and the engine was powered by an electric motor.


This train does need a table. The track is made of wood as is the train and it is powered by the little hands of a two-year old.

A nice train table and two storage boxes- were priced at $300. I thought that was way too high until I started building it. Building it yourself saves more than half the cost but after the rubber feet bumpers, casters, chalkboard paint, varnish, wood and miscellaneous materials were purchased we were $90 lighter in the pocket.

Before you rush out and spend money on materials be sure you have all the tools to build this project. At a very minimum you will need a table saw and belt sander. It is assumed you also have the normal assortment of hand tools. Electric drill, drills, screwdrivers, paint brushes, hammer, nails and so forth. You would do well to see about gaining access to a drill press to drill the holes through the legs. The legs need holes for screws. This allows you to break down the frame for transport or shipping. If you are going to use the table where you build it, or have a truck, it would certainly be possible to avoid the holes and screws and permanently mount the legs.

Chalkboard paint? Chalkboard paint is fairly common and makes a reasonably good chalkboard. We wanted the top of the table to be a chalkboard so that it could serve a double purpose.

I have also heard that you can make your own chalkboard paint. Here is a link that tells you how to do it.


Table top inside dimensions are 48 X 32 inches. This is the dimension of the top itself, before it is framed. The skirt keeps little train parts from falling to the floor. The top dimension is sized to allow colorful landscape posters to cover the top. Makes the train layout look more natural.


Here you can see the bolt holding the end piece to the table leg.


That is chalk on the chalkboard top. One of the ways of conditioning the blackboard is to cover it with chalk after the paint has cured for three days. Rub chalk all over it. Let it sit a few minutes. Then erase the chalk with a clean, damp rag. This was done before the final trim was installed around the table top. I have not figure out yet how to remove the chalk dust from the patio. I suspect a garden hose will be involved.

See the prevarnished lumber leaning up against the wall? That is the skirt material that will be installed around the table top. It is prevarnished so that we dont slop paint onto our blackboard top. Notice also that the skirt material is clear pine. No knots or imperfections. We cut that wood from a larger pine board on the table saw and discarded those parts that had knots. That is far less expensive than buying clear pine.


The chalkboard paint was also used on the storage box covers. So you can either sit on boxes with covers in place or draw on them with chalk or remove the covers and draw on them. Lots of possibillities.

The table legs are 3×3 inch pine and were made from two joined lengths of 2×4. The leg assembly is in four sections. Two of the sections had legs securely attached with glue and dowels. These two sections were fitted to the skirt framing the underside of the table top. Two additional end pieces are attached with bolts and T-nuts. The attachment can be seen in the pictures. A 1/4 inch diameter, 4 inch long bolt passes through the end skirt, through the leg and is screwed into the threaded T-nut that is installed into a hole in the far side of the leg. These holes almost have to be drilled on a drill press to keep them straight and true.

The wood is pine. The actual table top is hardboard that has had three coats of blackboard paint applied. The painted top is glued to a sheet of half-inch thick plywood for support. The finish is Minwax Honey Pine Stain & Polyurethane.

I did not even think of painting the plywood directly with chalkboard paint. My guess is that would not make a very good blackboard. The surface of my plywood was too rough and soft.

The hardboard is VERY hard and the finished side is VERY smooth. Excellent blackboard material. The hardboard blackboard is attached to the plywood with glue alone. Some clamping helps but I did not have the clamps required to seriously hold the parts together and had to rely mainly on gravity and some heavy concrete blocks.

Storage boxes are made from pine shelving. Mitered corners glued and held secure with dowels and more glue. Bottoms of the boxes are hardboard riding in a slot cut into the end and side boards before assembly. Tops covers are hardboard that has also been painted with chalkboard paint.