This single-Ended (SE) 6550 design is based on a minimonitor constructed by Lars Ohlsson of ElektroAkustik & Music.
The single-ended amplifier circuit uses a 6550 high power tetrode vacuum tube in the output stage. A 12DW7 or 7247 is used to drive the output stage. The 12DW7 / 7247 is a dual section triode, the first section has a gain factor of 20 and the second section a gain of 100. You can think of it as one-half of a 12AX7 and one-half of a 12AU7 in the same envelope. New production JJ ECC832 tubes are a suitable replacement for the 12DW7 and 7247 which are no longer in production. C2 and C3 should be good quality film capacitors. The cathode bypass capacitors C1 and C4 will also have some impact on the sound and good quality low ESR capacitors are suggested.
Single-Ended (SE) 6550 Tube Amplifier Schematic - [Link]
This is a new and improved version of “Warm Tube Clock” – the open source Nixie clock project. Important hardware changes between this new version and the previous one are:
- Timekeeping is more accurate and is done by DS3231 (or DS3232) RTC IC
- There is no DS18S20 temperature sensor – the internal one of RTC IC is used instead
- Backup battery is not powering AVR anymore, but only the RTC IC
- There is no “slide switch” to control the alarm – now it is done in firmware
- Crystal on PCB is optional and can be chosen up to 16 MHz. It clocks AVR and GSCLK pin of TLC59401 IC
- Pin-compatible with previous version of Nixie “shields”
Warm Nixie Tube Clock – [Link]
Gareth Branwyn writes: [via]
To follow the level of radioactivity in the Japanese capital, local makers are building DIY Geiger counters. A popular one seems to be the USB Geiger counter kit sold by Strawberry Linux. It’s a Geiger counter based on Geiger–Müller tube (or GM tube) that can be connected to a PC.
DIY Geiger Counters in Japan – [Link]
Enrico Mathesar writes:
This little gadget will simulate a 500 volt or less Geiger tube when driven by a signal generator of sufficient amplitude, typically 5 volts p-p or greater. The purpose is to generate a steady, precise number of counts per minute so that the Geiger counter’s meter may be calibrated.
Geiger Tube Simulator – [Link]
Seeed Studio is asking for help creating an open source radiation sensor, to help in the wake of the Japanese Tsunami. [via]
Can open hardware community do something to help in this? Seeed Studio is now sourcing sensors, then assemble quick measurement tools, ship as many/fast as possible to Japan.
Since we have no previous experience with such device, your help is needed!
If you have experience in making such device, some quick questions:
1. What would be the right sensor for such detection? Will the education purpose GM tube work?
2. Any recommended peripheral circuits?
3. Does such Geiger counter needs special calibration? Or can we calibrate it with commercial device?
All creations will be open source and donated, thank you for helping out!
Radiation detector, help needed! – [Link]
As soon as I heard about the 555 timer contest, I knew I had to come up with something inspiring! My buddy Jay recently introduced me to Nixie Tubes, and I thought… hmm, how can I use a tube and the 555 timer? I noodled on it for a while, and ultimately came up with the notion of a KEYCHAIN! Simple really, take the smallest Nixie Tube that displays digits, and make it display a ’5′ in the smallest package possible and put it on a keychain. That was the idea… and it took quite a journey to complete.
A Nixie Tube Keychain – [Link]
This project is a FM tuner with a Phillips FM1216ME_MK3 tuner module and 6H30 tube output buffer. The device is controlled by 18F452 PIC microcontroller and also has a RDS decoder with a TDA7330B and a 16F84A PIC.
FM tuner with Phillips FM1216ME_MK3 module - [Link]
Rudolf Moers from the Netherlands has kindly sent us details of his parallel push-pull 300B monoblock tube amplifiers to share with the DIY Audio community. It should be quite obvious from the photographs that the design and construction of a pair of amplifiers this size is by no means a small undertaking. Rudolf tells us that he spent about 14 months designing and constructing the pair of monoblock amplifiers. The total cost of each amplifiers was about 1300 Euro, or about $1760US as of 29 September 2010. Each monoblock weighs 25 kg (55 pounds) and the overall dimensions are 530 mm deep, 390 mm high, 400 mm wide.
Parallel Push-Pull 300B Tube Amplifiers - [Link]