Repairing A Junked Signal Generator

October 15, 2012 by Mike Szczys 21 Comments

We must be walking past the wrong dumpsters because we certainly haven’t encountered equipment like this just waiting to be salvaged. [Shahriar] found an HP 8648C Synthesized Signal Generator while he was ‘dumpster diving’ and set out to fix the malfunctioning lab equipment. He posted a 1-hour video on the project, which you can find embedded after the break. The actual fix happens in the first half, the rest of the video is spent testing the resurrected device.

The back corner of the case has been dented, which may be the reason this has been thrown out. When it is first powered it emits an unpleasant screeching noise and the user interface doesn’t do anything. [Shahriar] says he recognizes the sound as a malfunctioning switch-mode power supply. Sure enough, when disconnected from the main board it still makes the noise. It turns out there’s a huge electrolytic capacitor the size of a stack of poker chips which has come loose from the PSU board. When it’s resoldered the device fires up as expected.

Now how are we going to find a digital capture oscilloscope that just needs to have its PSU reassembled?

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Giving The Rigol DS1052E ‘scope A Spectrum Analyzer

October 10, 2012 by Brian Benchoff 16 Comments

Like a lot of hardware tinkerers, [dexter2048] has a Rigol DS1052E oscilloscope sitting on his bench. One day when trying to coax some information out of the FFT setting, [dexter] threw his hands up in frustration and decided to write a file viewer with FFT spectrum analysis. The resulting viewer gives this very capable and inexpensive oscilloscope a spectrum analyzer.

[dexter2048]’s app is able to capture signals from 0 Hz to 500 MHz and demonstrated this fact by sticking a piece of wire into one of the Rigol’s inputs. The resulting waveform is then sent to a computer where [dexter] got a nice picture of the radio spectrum between 82MHz and 114MHz. In his graph, you can clearly see the FM radio stations that can be picked up in [dexter]’s lab.

This small modification to the Rigol DS1052E oscilloscope it the latest in a long line of hacks that give this wonderful, inexpensive scope double the bandwidth, data collection via Python, and even a homebrew version of Pong. Anything that provides new functionality for old gear is great news to us, and we look forward to many, many more 1052E hacks in the future.

Tip ‘o the hat to [Murlidhar] for sending this in.

Oscilloscope VFD Repair Like Doing Brain Surgery On Yourself

October 9, 2012 by Mike Szczys 11 Comments

[Jerry Pommer] has an old Tektronix 2236 that is having some issues. Just to the right of the top corner of the screen is a VFD display that is used to show various numerical measurements. Unfortunately this has stopped working, so he made the oscilloscope probe itself in order to trouble-shoot the situation.

The entire repair process was filmed and you can see the 42-minute job embedded after the break. There’s a lot of stuff crammed inside that oscilloscope, and we see a tour of it all at the beginning of the video. Once [Jerry] gets down to business he traces the problem to a JK Flip-Flop used to feed the display. The output appears correct at first, but the clock signal is not functioning as expected. His solution is to use an MSP430 chip to replace the Flip-Flop functions.

The confidence to try this repair was sparked by [Todd Harrington’s] car-stereo VFD repair video.

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Dummy Load Uses Gray Code To Adjust Load In Small Steps

October 9, 2012 by Mike Szczys 10 Comments

We’re not really interested in building a dummy load like this one for ourselves. But the concepts behind its design make for a nice little mental exercise as you read your way through the build description. [Pabr] wanted to build a dummy load which could be used to test a cheaply made gas generator. He wanted it to be as simple as possible, while providing a range of different loads. What he came up with is this monotonically adjustable load tester which uses gray codes for switching.

The video after the break does a good job of explaining the motivation for the design. Grey coding ensures that just one bit changes at a time. The example he uses to show the importance of this is when binary code transitions from 7 (0b0111) to 8 (0b1000). Three digits have been turned off and one has been turned on. Since he’s using light bulbs for his load this will turn off 700 Watts and then switch on 800W. That sudden jump in power draw can cause all kinds of problems with the generator’s engine. But the system he wired up will ensure that each flip of a switch moves in smaller steps.

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Building Up An Inventory Of SMD Parts

October 8, 2012 by Brian Benchoff 57 Comments

Once you’ve been tinkering around with electronics for a while, you’ll realize the through-hole components that make breadboarding a circuit so easy won’t cut it anymore. Surface mount parts are the future, and make it incredibly easy to build a semi-professional mockup at home. The question arises, though: how do you store thousands of surface mount parts smaller than a grain of rice?

As [George] was building up his SMD inventory, he came across a few clever solutions. The first was a binder sold by Adafruit (and others) that holds strips of cut tape SMD components. [George] wanted something a little more modular, and when he came across an eBay auction for 5000 0805 resistors and 3000 0805 caps, he needed to find a storage solution.

[George] ran across these tiny modular boxes while shopping at Adafruit. These boxes are completely modular, interlock with each other, and have a hinged lid that will hopefully prevent the eventual, ‘SMD parts everywhere’ spill everyone his likely to have.

After printing out some labels for his boxes, [George] had a very tidy solution to his SMD organization problems. We’re wondering what other Hackaday readers use to organize their parts, so if you have a better solution send it in.

A Mobile Electronics Lab For All Your Projects

October 7, 2012 by Brian Benchoff 20 Comments

When [Nisker]’s son got a very, very loud and annoying toy, he did what any good maker parent would do: instead of removing the batteries, he sought a way to lower the volume instead. This, of course, meant cracking open the toy and going at the circuit board with a soldering iron. Not having a permanent electronics workbench meant [Nisker] needed to dig out his Weller from a bag full of tools. Surely there must be an easier way to be a tinkerer with a small workspace.

[Nisker]’s solution was to build a mobile electronics workbench. The resulting wooden box has more than enough space to hold a signal generator, power supply, soldering iron, multimeter, and a bunch of other tools required for making or modding electronics projects.

The case was designed in Google Sketchup and constructed out of 12mm plywood for the sides and 6mm ply for the shelves. All the pieces were cut out with a circular saw and pieced together with screws and glue.

Now [Nisker] has a very compact – 16.9 x 7.9 x 22 inches – electronics lab he can carry just about anywhere. Not a bad project if you’re limited by your current space, and classy enough to keep around once you finally set up a proper workshop.

Through-hole Electroplating In Your Home Lab

October 3, 2012 by Mike Szczys 19 Comments

For the few double-sided PCBs we’ve actually etched at home we simply soldered a piece of wire to either side of a via and clipped off the excess. But if you want to go the extra mile you can’t beat electroplated through holes. The setup seen above is an electroplating tank build from simple materials which [Bearmos] has been working on.

The two sets of copper structures are both used as anodes. Some copper water pipe (like you’d use for a refrigerator ice maker) was cut into short rods and soldered onto pieces of bus wire. The portion of the metal which will stick above the chemical bath was coated with a generous layer of hot glue. This will protect it from corrosion cause by the off-gassing during the plating process. The traces of the etched PCB act as the anodes, but the holes themselves must be conductive in order for the plating process to work. A water proof glue with powdered graphite mixed in is applied to all of the holes in the substrate. This technique is based on the huge electroplating guide published by Think & Tinker.