The State of Hollow State Audio in the Second Decade of the 21st Century
Vacuum-tube (or valve, depending upon which side of the pond you live on) technology spawned the Age of Electronics early in the 20th Century. Until the advent of solid-state electronics near mid-century, hollow-state devices were the only choice. But following the invention of the transistor (after their process fell to reasonable levels), within a couple of decades, the death of vacuum tubes was widely heralded. Yet here we are some five decades later, and hollow-state equipment is enjoying something of a comeback, especially in the music and high-end audio industries.
Many issues surround hollow-state audio:
Does it produce—as some claim—better sound? If so, is there science to back up these claims?
How do hollow-state circuits work?
How do you design hollow-state audio circuits?
If hollow-state equipment fails, how do you go about troubleshooting and repairing it?
Can we recreate some of the classic hollow-state audio devices for modern listening rooms and recording studios?
How can we intelligently modify hollow-state amplifiers to our taste?
These and other topics are covered in The State of Hollow State Audio.
Whatever the methods or even then financial means you have to make your circuits work, the power supply should rank high if not Number One in your considerations. The design block simply called “power supply” is hugely underrated both in electronics creation and repair. Yet, the “PSU” has enormous diversity and comes in wildly differing guises like AC/DC, generator, battery (rechargeable or not), PV panel, benchtop, linear or switch-mode, to mention but a few. The output ranges are also staggering like nano-amps to kiloamps and the same for voltages.This special covers the features and design aspects of power supplies.ContentsBasics
Battery ManagementWhat to be aware of when using (Lithium) batteries.
Fixed-Voltage Power Supply using Linear RegulatorsThe best result right after batteries.
Light Energy HarvestingA small solar panel is used in an energy harvesting project to manage and charge four AAA cells.
Mains Powered Adapter DesignBasic circuits and tips for transformers, rectification, filtering and stabilization.
LM317 Soft StartThe high inrush current pulse should be avoided.
Controllable RectifiersSome suggestions to keep the power loss in the linear regulator as low as possible.
Components
Worksheet: The LM117 / LM217 / LM317 Voltage Regulators
SupercapsLow voltage but lots of current… or not?
Reviews
JOY-iT RD6006 Benchtop Power Supply Kit
Siglent SDL1020X Programmable DC Electronic Load
Projects
Balcony Power PlantDIY solar balcony = speedy payback!
DIY LiPo Supercharger KitFrom handcrafted to mass market
Dual-Anode MOSFET ThyristorFaster and less wasteful than the old SCR
Battery JuicerDo not throw away, squeeze!
High-Voltage Power Supply with Curve TracerGenerate voltages up to 400 V and trace characteristics curves for valves and transistors
High Voltage Supply for RIAAFor RIAA tube preamps and other applications.
MicroSupplyA lab power supply for connected devices
Phantom Power Supply using Switched CapacitorsVoltage tripler using three ICs
The SMPS800RE Switch-Mode Supply for the Elektor Fortissimo-100Reliable, light and affordable
Soft Start for PSUBe nice to your power supply – and its load
UniLab 20-30 V, 3 A compact switch-mode lab power supply
Tips
Soft Start for Step-Down Switching Regulators
Low Loss Current Limit
Powerbank Surprise
A Virtual Ground
Battery Maintainer
Battery Pack Discharger
Connecting Voltage Regulators in Parallel
Temporary Delay in the Delivery of Unitree Robots
Like many other suppliers, we are currently experiencing delays in the delivery of Unitree robots. A shipment from our supplier is currently held in customs, which has unfortunately led to later-than-planned deliveries for previously placed orders. We are actively working with our supplier to resolve this issue and expect more clarity soon, but at this time, we cannot provide any guarantees.
Additionally, a new shipment is already on its way, though it will take some time to arrive. Since other suppliers are facing similar challenges, switching to a different provider is unlikely to result in a faster solution. Our top priority remains fulfilling existing orders.
If you have any questions or would like to update your order, please do not hesitate to contact our customer service team. We will keep you informed of any further developments.
Unitree Go2 series consists of quadruped robots for the research & development of autonomous systems in the fields of human-robot interaction (HRI), SLAM & transportation. Due to the four legs, as well as the 12DOF, this robot can handle a variety of different terrains. The Go2 comes with a perfected drive & power management system, which enables a speed (depending on the version) of up to 3.7 m/s or 11.88 km/h with an operating time of up to 4 hours. Furthermore, the motors have a torque of 45 N.m at the body/thighs and at the knees, which also allow jumps or backflips.
Features
Super Recognition System: 4D LIDAR L1
Max Running Speed: approx. 5 m/s
Peak Joint Torque: approx. 45 N.m
Wireless Module: WiFi 6/Bluetooth/4G
Ultra-long battery Endurance: approx. 2-4 h (long battery life measured in real life)
Intelligent Side-follow System: ISS 2.0
Specifications
Tracking module: Remote-controlled or automatic tracking
Front camera: Image tansmission Resolution 1280x720, FOV 120°, Ultra wide angle lens deliver rich clarity
Front lamp: Brightly lights the way ahead
4D LiDAR L1: 360°x90° omnidirectional ultra-wide-angle scanning allows automatic avoidance with small blind spot and stable operation
12 knee joint motors: Strong and powerful, Beautiful and simple, Brandy new visual experience
Intercom microphone: Effective communication with no scenario restrictions
Self-retracting strap: Easy to carry and load things
More stable, more powerful with advanced devices: 3D LiDAR, 4G ESIM Card, WiFi 6 with Dual-band, Bluetooth 5.2 for stable connection and remote control
Powerful Computing Core: Motion controller, High-performance ARM processor, Improved Al algorithm processor, External ORIN NX/NANO
Smart battery: Standard 8000 mAh battery, Long-endurance 15000 mAh battery, Protection from over-temp, overcharge and short-circuit
Speaker for music play: Listen to music as your pleasure
Unitree Go2 Variants
The Go2 impresses not only with its technical capabilities, but also with a modern and slim design that gives it a futuristic look and makes it a real eye-catcher. The Go2 Air is specially designed for demos and presentations. With its basic features, it offers a solid basis for demonstrating the movement capabilities and functionality of a four-legged robot. Important: The Go2 Air is delivered without a controller. This can be purchased optionally.
With a powerful 8-core high-performance CPU, the Pro and Edu offer impressive computing power required for complex tasks and demanding calculations. This enables faster and more efficient data processing and makes the Pro and Edu a reliable partner for your projects.
From the Edu version onwards, the Go2 is programmable and opens up endless possibilities for developing and researching your own robotics applications. The Go2 is also able to handle a step height of up to 14 cm. This makes it an ideal tool for research, education and entry into the world of robotics.
The Go2 Edu comes with a remote controller that gives you easy and intuitive control. You also get a docking station with impressive computing power of 100 TOPS, which is equipped with powerful AI algorithms and offers you technical support.
Go2 Edu is equipped with a powerful 15000 mAh battery that gives it an impressive runtime of up to 4 hours. This long operating time allows the robot to carry out longer exploration missions and complete demanding tasks.
Model Comparison
Air
Pro
Edu/Edu Plus
Dimensions (standing)
70 x 31 x 40 cm
70 x 31 x 40 cm
70 x 31 x 40 cm
Dimensions (crouching)
76 x 31 x 20 cm
76 x 31 x 20 cm
76 x 31 x 20 cm
Material
Aluminium alloy + High strength engineering plastic
Aluminium alloy + High strength engineering plastic
Aluminium alloy + High strength engineering plastic
Weight (with battery)
about 15 kg
about 15 kg
about 15 kg
Voltage
28~33.6 V
28~33.6 V
28~33.6 V
Peaking capacity
about 3000 W
about 3000 W
about 3000 W
Payload
≈7 kg (MAX ~ 10 kg)
≈8 kg (MAX ~ 10 kg)
≈8 kg (MAX ~ 12 kg)
Speed
0~2.5 m/s
0~3.5 m/s
0~3.7 m/s (MAX ~ 5 m/s)
Max Climb Drop Height
about 15 cm
about 16 cm
about 16 cm
Max Climb Angle
30°
40°
40°
Basic Computing Power
N/A
8-core High-performance CPU
8-core High-performance CPU
Aluminum knee joint motor
12 set
12 set
12 set
Intra-joint circuit (knee)
✓
✓
✓
Joint Heat Pipe Cooler
✓
✓
✓
Range of Motion
Body: −48~48°
Body: −48~48°
Body: −48~48°
Thigh: −200°~90°
Thigh: −200°~90°
Thigh: −200°~90°
Shank: −156°~−48°
Shank: −156°~−48°
Shank: −156°~−48°
Max Torque
N/A
about 45 N.m
about 45 N.m
Super-wide-angle 3D LiDAR
✓
✓
✓
Wireless Vector Positioning Tracking Module
N/A
✓
✓
HD Wide-angle Camera
✓
✓
✓
Foot-end force sensor
N/A
N/A
✓
Basic Action
✓
✓
✓
Auto-scaling strap
N/A
✓
N/A
Upgraded Intelligent OTA
✓
✓
✓
RTT 2.0 Image Transmission
✓
✓
✓
App Basic Remote Control
✓
✓
✓
App Data Viewing
✓
✓
✓
App Graphical Programme
✓
✓
✓
Front Lamp (3 W)
✓
✓
✓
WiFi 6 with Dual-band
✓
✓
✓
Bluetooth 5.2/4.2/2.1
✓
✓
✓
4G Module
N/A
CN/GB
CN/GB
Voice Function
N/A
✓
✓
Music Playback
N/A
✓
✓
ISS 2.0 Intelligent side-follow system
N/A
✓
✓
Intelligent detection and avoidance
✓
✓
✓
Secondary development
N/A
N/A
✓
Manual controller
Optional
Optional
✓
High computing power module
N/A
N/A
Edu: 40 TOPS computing power
Edu Plus: 100 TOPS computing power
NVIDIA Jetson Orin (optional)
Smart Battery
Standard (8000 mAh)
Standard (8000 mAh)
Long endurance (15000 mAh)
Battery Life
1-2 h
1-2 h
2-4 h
Charger
Standard (33.6 V, 3.5 A)
Standard (33.6 V, 3.5 A)
Fast charge (33.6 V, 9 A)
Included
1x Unitree Go2 Edu
1x Unitree Go2 Remote Controller
1x Unitree Go2 Battery (15000 mAh)
1x Unitree Docking station with 40 TOPS computing power
Downloads
Documentation
iOS/Android apps
GitHub
Menno van der Veen is well known for his research publications on tube amplifiers used in audio systems.
In this book he describes one of his research projects which focuses on the question of whether full compensation for distortion in tubes and output transformers is possible.
In the past, a variety of techniques have been developed. One of them has largely been forgotten: trans-conductance, which means converting current into voltage or voltage into current. Menno van der Veen has breathed new life into this technique with his research project titled “Trans”. This book discusses all aspects of this method and discusses its pitfalls. These pitfalls are addressed one by one. The end result is a set of stringent requirements for Trans amplifiers.
Armed with these requirements, Menno then develops new Trans amplifiers, starting with Transie 1 and Transie 2. These DC-coupled, single-ended tube amplifiers have unusually good characteristics and are suitable for hobbyist construction. Next the Trans principle is applied to amplifiers with higher output power.
A trial-and-error process ultimately leads to the Vanderveen Trans 30 amplifier, which optimizes the features of Trans. The characteristics of this amplifier are so special and unique that Menno believes he has struck gold. To ensure that variations in tube characteristics cannot interfere with optimal Trans behavior, Menno makes use of simulations and comparison with other amplifier types. This book reads like an adventure story, but it is much more – it is an account of solid research into new ways to achieve optimal audio reproduction.
Need to dispense your own UV sensitive fluids (up to 550nm)?
Included
4x 5cc UV-Blocking Syringe Barrels
4x Standard Fit Pistons (white)
4x High Viscosity Fit Pistons (red)
4x Tip Caps
4x End Caps
2x Female to Female Luer couplers
This set contains 3 desoldering tips for digital desoldering stations such as ZD-915 or ZD-8965.
Included
1x Desoldering tip N5-1 (0.8 mm)
1x Desoldering tip N5-2 (1.0 mm)
1x Desoldering tip N5-3 (1.3 mm)
This set contains 3 nozzles for Hot Air Rework Stations such as ZD-8922 or ZD-8968.
Included
1x Hot air nozzle 79-3911
1x Hot air nozzle 79-3912
1x Hot air nozzle 79-3913
SMA Straight Plug to SMA Straight Plug, 76.2 mm
Specifications
Frequency range
0 to 18 GHz VSWR (≤1.35)
Insertion loss
≤0,22 db
Body
Brass Nickel
Centre contact
Brass Gold
Insulator
PTFE
UFactory 850 is the most powerful robot with industrial grade performance.
Features
6DoF
Payload: 5 kg
Reach: 850 mm
Repeatability: 0.02 mm
Weight: 20 kg
Applications
Glambot
Welding
Screwdriving
Robot Vision
Industrial Production
Designed for both mobile platforms and your workbench
The AC control box contains an AC-DC adapter inside, 100-240 V AC is all ready to go.
The DC control box supports 48-72 V wide inputs, it perfectly fits the battery system on your mobile platform.
Flexible Deployment With Safe Feature
Hand teaching, space-saving and easy to re-deploy to multiple applications without changing your production layout. Perfectly for recurrent tasks.
Collision detection is available for all of our cobots. Your safety is always the top priority.
Graphical Interface For Beginner-Friendly Programming
Compatible with various operation systems, including macOS and Windows.
Web-based technology compatible with all major browsers.
Drag and drop to create your code in minutes.
Powerful And Open Source SDK At Your Fingertips
Fully functional open-source Python/C++ SDK provides more flexible programming.
ROS/ROS2 packages are ready-to-go.
Example codes help you to deploy the robotic arm smoothly.
Specifications
UFactory 850
xArm 5
xArm 6
xArm 7
Payload
5 kg
3 kg
5 kg
3.5 kg
Reach
850 mm
700 mm
700 mm
700 mm
Degrees of freedom
6
5
6
7
Repeatability
±0.02 mm
±0.1 mm
±0.1 mm
±0.1 mm
Maximum Speed
1 m/s
1 m/s
1 m/s
1 m/s
Weight (robot arm only)
20 kg
11.2 kg
12.2 kg
13.7 kg
Maximum Speed
180°/s
180°/s
180°/s
180°/s
Joint 1
±360°
±360°
±360°
±360°
Joint 2
-132°~132°
-118°~120°
-118°~120°
-118°~120°
Joint 3
-242°~3.5°
-225°~11°
-225°~11°
±360°
Joint 4
±360°
-97°~180°
±360°
-11°~225°
Joint 5
-124°~124°
±360°
-97°~180°
±360°
Joint 6
±360°
±360°
-97°~180°
Joint 7
±360°
Hardware
Ambient Temperature Range
0-50°C
Power Consumption
Typical 240 W, max 1000 W
Input Power Supply
48 V DC, 20.8 A
Footprint
Ø 190 mm
Materials
Aluminum, Carbon Fiber
Base Connector Type
M8x4
ISO Class Cleanroom
5
Robot Mounting
Any
End Effector Communication Protocol
Modbus RTU
End Effector I/O
2x DI / 2x DO / 2x AI / 1x RS485
Communication Mode
Ethernet
Included
1x UFactory 850 robotic arm
1x AC control box
1x Control box power cable
The official Raspberry Pi micro HDMI to HDMI (A/M) cable (black, 1 m) designed for the Raspberry Pi 4 and 5.
19-pin HDMI Type D(M) to 19-pin HDMI Type A(M)
1 m cable (black)
Nickel-plated plugs
4Kp60 compliant
RoHS compliant
3 Mohm 300 VDC insulation, withstands 300 VDC for 0.1s