Julian's Home Page

This is a new project, started in October 2009

The photo below shows my completed Minisonic2 sound synthesizer, which follows Doug Shaw's original design published in Practical Electronics in the early 70s.

My Nixie tube clock.

I found a nice little box to put it in in a shop in France. The biggest challenge was drilling the required 1" diameter holes (I ended up using a Forstner bit). Here are the guts:

At the top left hand corner is the power supply, which produces 250V DC regulated no load. Underneath is the clock board, which uses a programmed PIC to generate the required signals for the tubes. Then you see the four tubes at the bottom, with the cathode wires and multiplex anode feed wires attaching them to the clock board. There are also two LEDs, in the centre of the tubes, one of which flashes seconds, the other flashes half seconds. The two switches in the top right hand corner are used to set the time and control the brightness of the tubes.

 

Here is the completed clock as installed in the sitting room, next to an old writing cabinet.


I can't tell you how much fun making this clock was, and what a pleasure it is to see the warm glow of the Nixies telling the correct time :-)

My Single Ended Stereo Tube Amplifier.

Uses a 6SN7GT as a pre-amp, and doubled-up 6GF7A triodes as the power stage.

More details, including schematic, here.

A spectrum analyzer I made in about 1990.

It was built for 220 Volts mains, and included a 9V rectifier.

The wiring is what I would call "Boutique", as you can see from this photo:

The audio input is fanned out into five separate bandpass filters of my own design. Each filter is based around a 741 opamp, and tuned to a different frequency from the rest. The output from each filter is fed to a set of five LM341 LED driver ICs which each turn a bank of 10 LEDs on depending on the output level. The 341 can run in two modes: the first mode lights just the LED corresponding to the output voltage, the second lights that LED and all below it. I had a switch to select between the two.

In this image the LEDs are in the second mode, and the Analyzer is responding to a 5kHz sine wave input.

My design had several flaws, most serious was that there was interference between the lowest two banks of LEDs. I think the filters are very wide, and I was too ambitious in tuning their centre frequencies. The result is that, for low frequency inputs, the lowest LED banks oscillate in brightness.
 

Vacuum Tubes / Valves

Table of the my vacuum tubes (or valves). Here is the spreadsheet.

Table of my transistors. Here is the spreadsheet.

Precision Tube Testers

A web page devoted to the various models of Tube Testers made by the Precision Apparatus Corporation, who were eventually bought up by B&K Instruments

Here's a picture of my Precision 660 ... this is different from all other 660s I've seen in that it has more transistor and tube sockets. I refurbished the case, since the original cloth-like covering was very tatty. To do this I removed all the material, sanded down the surfaces, and applied three coats of Danish Oil.

More pictures here, including showing the instrument testing a 6SN7GT dual triode: (click on thumbnails for larger versions)

Lloyd's Solid State 5 Band Receiver

Ebay: $4.99

9H34W-34A five band receiver. The five bands are:

1. AM Broadcast
2. FM Broadcast
3. Citizen’s Band
4. Aircraft 108 to 135 MHz
5. Public Safety 149 to 173 MHz

Tektronix Oscilloscopes

Take a look at my collection of Tektronix oscilloscopes and Plug Ins.

Look at the knob count on this baby - my Tektronix 556 Dual Beam 'scope.

Here's an image of the 556 in use, testing the Minisonic2

My 214 mini storage 'scope

Here's my 310A, 516, 5441, 561A, 321A, 310 and 575 curve tracer

The 7D20 plugged in to my 7904 mainframe:

Full details on all these Tektronix scopes is here.

Here's a TS-34A military 'scope dating from 1953, in working condition. I have the original manual for this 'scope: the scan is here.

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Here's my Telequipment S-43. There are two other plugins for this 'scope in my collection.

Solartron Oscilloscope

This is a pic of a Solartron 'scope identical to one I had as a boy. I believe these were used by the British Navy. I cannot recall the model number, but it was perhaps an OS-20?

My dad and I drove down to Dartford (South London) to buy it. When we arrived, the guy had around six for sale, and another he was using on his workbench for himself. My dad and I checked each of the
others, and none of them worked properly, so we ended up with the one the guy was using (we'd come a long way, and I think he was a bit sheepish about how the rest didn't work)!

MJS Sweep Marker Generator

Hewlett Packard 608C VHF Signal Generator

Above picture shows the generator as received. Below shows the generator after repainting, face cleaning etc.

Look at the engineering inside (there are several belts and pulleys)

I checked the performance using my Leader digital frequency meter: the 608C produces beautiful sine waves and is accurate up to at least 90Mhz (the limit of the Leader). The front panel meters correctly show the modulation and output signal levels. Somebody said that by using the analogue modulation input on the 608C it would be possible to broadcast video to a nearby TV!

The manual for the 608D (very similar to the 608C, but features a crystal marker) is here.

The manual for the similar MS-230 is here (it is also on BAMA). Thanks to Marvin Moss.

Here is the schematic for the MS-15. And another version.

 Sony TC-399 Reel to Reel tape deck

Information on the TC-399 can be found here.

Transistor Tester

My SECO Transistor and Tunnel Diode tester, Model 250.

Resistance/Capacitance Tester

My Knight R/C checker came with a 6E5 Magic Eye tube. Here's an animated GIF of the tube as the checker moves through the correct measured resistance value:

Allied Knight R100 Communications Receiver

This communications receiver, dating from about 1957, includes an S-meter and crystal calibrator.

More details here.

See here for more details.

SX-71 (Run4):

SX-28:

SX-110:

SP-44:

R-46:

SX-71 (Run3):

S-107:

S-40A:

WR-600:

5R10A:

SX-130:

5R100A:

Aligning the HQ-110C with sweeps.

WinAIRR and AIRR (Anechoic and In-Room Response)

An article published in Speaker Builder Magazine describing AIRR, software for measuring loudspeaker response using a SoundBlaster card. The more recent version for Windows: WinAIRR.

"APPENDIX C: HYPERTEXT / HYPERMEDIA R. Cailliau
A PROPOSAL FOR A NEW PROJECT

Hypertext is a form of information storage that is a web of interconnected nodes. The nodes contain information of some kind (document, program, picture, sound, ...), the web lines are ways of getting from one node to another. Searching in hypertext is aided by various mechanisms, each of different speed and efficiency (there can be indexes and keyword lists). However, the user can also navigate by following paths or just hopping along existing links in a random manner. Thus there are no restrictions on how a node of information is reached (in more classical systems one usually has to know part of the location of the information). In addition, users can construct their own additions to the set of links. The information nodes reside on different machines, the links across machines are handled by hypertext servers resident in the machines.

In the context of LHC practically all information will have been generated by machine. However, there is no unified way of accessing this information by machione: different platforms are used and different formats have been used to create the documents. Hypertext seems at the right stage of maturity to introduce it as the unification of these otherwise incompatible sources of data.

The pilot project would aim at giving a minimum level of access to LHC related information from any workstation. No attempt would be made to implement a large range of features, thus one would not provide uniform access to bitmapped pictures on all platforms, or to fully formatted text, since the formats for pixels, character fonts etc. are too divergent on different systems. However, one would attempt to provide
for a small number of the most popular formats, and just use plain alphanumeric text in other cases. This is the only road to success.

Phases are:

- look at commercial products & get educated,

- select the level of services that can reasonably be implemented and the platforms on which they would be provided,

- buy all components that can be bought,

- integrate,

- populate.

Population should be done by incorporating existing documents only. The first phase takes about 6 months.

The introduction of this technique cannot be done in isolation for one project: it has to be done in conjunction with other services and groups such as CN, the administration of CERN, and the accelerator divisions. Technical details of the project are to be found in a proposal by T. Berners-Lee of CN, with whom I would work closely."

2) Cost of intrusions/hackers on CERN VAX Clusters, 1992

3) Report on trip to DEC, 1992, information on Alpha chips, GIGASwitch, and other NDA

4) Trip report from 1996, visit to MIT Media Lab, DEC sites, etc. other NDA

This is an amusing story I was told about Klein. I have no idea if it's true, or not.

An HP salesman came to CERN with one of HP's very first digital calculators, which were exciting a lot of interest in the science community at the time The DG himself arranged a demonstration, and invited
all the Directorate. The room was very crowded. The HP guy set up the machine, and when he was ready, asked the audience for two many-digit numbers to multiply together. Wim Klein had meanwhile come into the room unnoticed, wondering what the crowd was looking at. Somebody suggested a couple of large numbers, and the HP guy started to key them in to the calculator. And before he'd even finished keying, Wim Klein shouted out the answer from the back of the room!