It’s nice to know that the death of celebrity can cause Twitter, Google, Wikipedia, and other major sites to grind to a halt and fail. Robust infrastructure, indeed.

We’ve had an unusually hot summer so far, with another day of record heat (105 degrees at 4 PM). It’s the longest/hottest stretch of weather we’ve seen since our arrival in Austin. And very little rain, so our front yard is turning into a desert. (It was already very scrubby and junky.) The back yard is holding up okay, though I think I need to water our two pine trees. They are looking pretty sad.

Our friend Debbie was in town over the weekend, which was nice. She came down to visit & to have me fix her PCs. She also took the opportunity to eat out as much as possible, since there is not much variety where she lives. On Monday we went out toward Llano, had some authentic Texas BBQ, and then took the tour of the Longhorn Caverns. It was a cool relief from the heat of the day, and Deb was able to confirm that we do indeed have hills in Hill Country. At least west of Austin.

Things have been quite hectic as of late. Last Thursday I quit my cushy job, having had enough. When you are 1200 miles from the corporate office, work at home, aren’t a manager, and your job still makes you mean and keeps you up at night, then you know it’s time to go! It’s a real gut-churner to quit a secure job in this economy, but I couldn’t deal with the situation much longer without feeling like a hypocrite.

Over the past week I’ve been regrouping, cutting off unnecessary expenses, and starting to think about “what’s next?” We have enough savings to keep us going for a while, so I have time to cast an eye out for things that I might not normally. The big question, as usual, is if I stay in IT. Pro: It pays. Con: It sucks. For now I’ll take some part-time contract jobs to cover the bills, while I mull over options. I’m seriously considering looking into becoming a machinist, perhaps in aerospace.  Who knows. Cooking is always an option, but master machinists get paid better. I want to enjoy myself, but I don’t want to be poor.

Got everything connected and wired up and things are looking good. Here is the “rats next” of the inside.

Atom Amp - Inside Guts

For now, I just zip-tied the board to the side of the speaker. There’s a piece of foamboard in between to protect it from shorting. Not pretty, but it works for now. I’m working on a cleaner way of doing this–probably mounting the board on stand-offs above the pots.

In the lower part of the photo you can see the battery pack. I’m using 8 AA batteries instead of a 9 V battery. Why? Because they will give 12 Volts, so the amplifier circuit will have a bit more headroom. Also, they have more amp hour capacity than a single 9V, so the batteries will last longer.

Here is the beast all sealed up:

Atom Amp - Back Together

Hidden in the shadow is the 1/4″ jack, which you can see more clearly in an earlier photo. From left to right you have Gain (a “booster”), Combined Volume & Power, and then the speaker. Those two wires/LEDs you see are a lighting assembly I’m toying with. They will light up when the power is on.

Right now I’m trying to find a suitable material for the speaker grill, to cover up that hole. Maybe a metal mesh, like in car speakers. I’ll have to look around and see if I can find a junked one somewhere.

Here is the amp standing up. I like how it is heavy and stable enough to stand on its own, either on the floor or on a table. It’s waiting for the final touches:

Atom Amp - Standing Up

I breadboarded the Ruby circuit twice this morning. Why twice? Well, because my big powered breadboard is acting up, as breadboards are want to do. So, I had to redo the whole thing again. I wanted to build out the prototype circuit first, as we’ve found that a lot of examples on the net don’t work! Always test it out first.

After the second round, I powered up everything and it worked. Horray! Next, I built out the actual perfboard soldered circuit. Here is the finished product:

Atom Amp : Ruby Amplifier Circuit

It was all point to point wiring. Not the neatest, but it works. I do use Molex connectors for everything. I’m not a big fan of directly wiring things to the board. Mainly due to past experience — it’s a lot easier to take things apart to debug when you have connectors.

There are connections for Input, Volume, Gain, Power, Speaker Out, and Aux Power (for driving other things like LEDs). The chip in the middle is the LM386 audio amplifier. Toward the upper left, near VOL, is the FET. The rest of the stuff is just caps, resistors, and wires. Layout, as usual, took the most time.

You have to be careful when doing audio amps, especially those with high gain. They are prone to noise and powerline hum. For example, if you have a long lead (like a alligator clip cable) attached to the input, you can pick on AM radio stations! It’s quite a little booster for its size.

Here are the controls, with wires braided and Molex connectors installed:

Atom Amp - Inside Wiring - With Molex Connectors

Next up, putting it all together.

Some of the parts I was waiting on arrived today, so I was able to start wiring up the front control panel. As you can see, I’m trying to re-use the existing knob placements:

Atom Amp - Front Panel - In Progress

The knob to the left will be the Volume control and the on/off switch. I am using a potentiometer with an integrated switch, much like you’d find in a radio. It saves having to have another switch crowding the front panel.

The smaller knob to the right of volume is the Gain control. For guitar amps, the two will work together. You can go from clean sounds to overdrive. A lot of twisting and turning will get you different sounds. The Gain knob is mounted in a new hole that I drilled.

The lower right area is where the 1/4″ jack is at, for connecting the guitar or other instrument. This is where that little knob used to live, but it’s a better location for the jack.

On the underside you can see that I’ve started some of the wiring:

Atom Amp - Front Panel - Underside - Wiring

From left to right you have volume/power, gain, and the 1/4″ jack in upper right.

You can see that I had to grind away quite a big of material so that the pot could be fastened in place. Why? Because the original unit was designed to be waterproof, so it had gaskets in there and pots with long shafts. The metal work on this project is probably the hardest part so far. In the above photo you can also see a closer look of the drilled and tapped holes for the speaker (removed in this photo–left side).

I also received the parts I needed for the amplifier circuit. I went with a design called Ruby. It’s a LM386 audio amp (very standard part) with a MPF102 FET as an input buffer. This combo is supposed to give a “Fender-ish” sound. You can read more about it here: Ruby Amplifier

A while back Evelyn picked up one of these Ion Chamber Survey Meters at the Citywide Garage Sale:

Atom Amp : The Original Device

The device is in good shape, cosmetically, but it has long given up the ghost. Ion Chambers are the dead man’s Geiger Counter. I say dead man’s because if you are getting a high reading on an Ion Chamber, you probably don’t have long to live anyway. It’s pretty much theater, just like the phony “security” of today. Something to keep the CD people busy.

Anyhow, it’s been sitting on a shelf for a while now. I was thinking of making it into some sort of weird clock, but with only one dial, that’s a little hard, and not very eye catching. Plus, it wouldn’t put to good use the cool Cold War retro vibe.

As happens quite often, another project gave me an idea for this device. You see, Evelyn and I are planning our next SkillShare workshops, and one idea was to do an electric cigar box guitar. Well, in order to use an electric guitar, you need an amp, right?

I have a good supply of speakers on hand, for our syth projects. So, I pulled out a 4 inch midrange and realized that it was EXACTLY the right size to fit into the meter! Even the mounting holes were perfect! And the meter could be removed and a speaker grill replaced. Horray! An idea is born.

Here’s the Survey Meter with the existing meter and knobs removed:

Atom Amp : Meter Removed

I’m going to put the 1/4″ jack in the hole that already exists (the “ZERO”). Probably volume and/or tone in the center hole.

Next, I had to cut back the stand-offs so that the speaker would fit. In this shot you can see that I have cut them back (with MANY broken Dremel cutoff wheels).

Atom Amp : Standoffs Cut Off And Tapped

After being cut (you can see the original length to the right of the above photo), I drilled and tapped four holes for mounting the speaker. Again, by amazing chance, the speaker mounts are exactly the right size. It was meant to be. Tapping is the process of creating threads in a material, so that you can use a machine screw to hold things together. If you are doing any sort of maker-type work, you need to get yourself a little drill and tap set. (I usually drill and tap. I rarely use dies, because I’m mostly making holes for regular screws to go into. McMaster-Carr sells an inexpensive, made in the USA, set of really small taps.)

An aside: As you can see, this is a destructive project. I cut the standoffs, so I’m not going to be able to turn this devices back into an Ion Chamber again. Normally I don’t do this, because I have a lot of respect for older stuff. However, when a piece of equipment has given up the ghost, and it’s not rare (this device is VERY common), I’m okay with repurposing. If this were a real Geiger Counter I would have fixed it instead of repurposing.

Now that the speaker mounting holes were drilling, and tapped (inside threads created), I was ready to mount the speaker. I used a couple of little plastic stand-offs, some machine screws, and washers. Here is the result:

Atom Amp : Speaker Mounted

As you can see, I used a nice mid-range speaker, with a big ass magnet. Again, it perfectly fits into the case, with plenty of room for the amp, pots, switches, battery, etc.

Next up: The electronics. Finding the right amplifier circuit, getting it wired up, and installing. More to come.

This evening I took a few minutes to wire up the PC and get everything assembled. Here is the result:

Electronics Crash Cart : Completed

Now we have a rolling computer with dual 19″ monitors in the garage.