RASON Projects Page

Designing Bipolar Transistor Audio PreAmps, Designing JFET Transistor Audio PreAmps, Designing Op Amp IC Audio PreAmps, Switching Regulator Basics, Using Transistors As Switches.

RASON Projects Page – Amateur Radio

  • 10 Amp, 13.8 Volt Power Supply
  • 12 Volt Gel Cell Charger
  • Thermal Fan Controller
  • Transistor Audio Amplifiers
  • 12 Volt Gel Cell Charger
  • Switching Regulator Basics

 

A Potpourri of Audio Amplifiers  By N1HFX

“I intentionally avoided the use of IC amplifiers to provide a real learning experience for audio amplifier design. Although many IC amplifiers provide excellent performance at low cost, we need to learn the basics first. I will address IC audio amplifiers in a future article.”

The Radio Amateur Society of Norwich
P.O. Box 329 – Norwich, Connecticut 06360

Elliott Sound Products – The Audio Pages

There is a very wide range of power amplifiers, preamps, guitar/ bass amplifiers, studio equipment, effects, and other projects to build, including loudspeakers, subwoofers, and many others

Elliott Sound Products – The Audio Pages

Elliott Sound Products - The Audio Pages

  • Projects – Complete listing of ESP’s free project and design articles
  • Articles – Informative articles about audio, building projects, and electronics in general
  • Buy PCBs for ESP Projects – boards supplied have very comprehensive documentation.

ESP Resource of Rod Elliott –  The above pages has many useful ideas and practical tips – delabs

It is by Hobby and DIY – Do it Yourself, Education Starts even without books. Then you need to read to enhance your abilities to Design your own.

In order to compensate or enhance your education, you need to work at a small shop as an apprentice even as a student, not for the sake of project work alone. An Evening job at a factory or a home mini workshop-lab is very essential for obtaining the skills – Solderman 1702

Experiments with the LM2575

The standard buck regulator circuit delivers a +5V output. This is a rather straightforward circuit and will operate with a wide spread of component values. Optimal values should be selected however to get minimal ripple, minimal noise to the power source, maximum efficiency etc. Note that the quiesent current is about 10 to 14mA.

Experiments with the LM2575

Here is a nice way of using this regulator, this can be used for CMOS opamps as you have a -5V too. That means a portable instrument may find this design useful.

The TI Datasheet Layout Guidelines

LM2575 Switching Regulator
LM2575 – Step-Down Adjustable Voltage Switching Regulator with Output Enable

 The Spirit of Hacking and Fixing, Giving back Life to Old Instruments.

Fluke 8050A LCD display replaced with LED seven-segment

“Recently I was able to cheaply buy a second hand Fluke 8050A made in the early eighties. It is a nice 4.5 desktop digit meter, but a typical problem seems to be that the LCD wears out and goes black. Replacement LCD displays are hard to find, not cheap and probably lead to similar problems in due time.”

Low Cost AM FM Stereo Receiver

This was a National Semiconductor Application Note, now TI. – Low Cost IC Stereo Receiver.

AN-147 Low Cost IC Stereo Receiver

Some Highlights

The LM3089 FM IF System does all the major functions necessary for FM processing, including a three stage amplifier/limiter and balanced product detector, as well as an audio preamplifier.

FM stereo demodulation is accomplished by the use of the LM1800 phase locked loop, thereby eliminating the need for external coils.

The AM function of the receiver is done completely with the LM3820 AM radio system. While designed for 3 section tuned superheterodyne application.

The LM382 dual preamplifier was selected for its minimum parts count and low noise capability.

Panel meters are employed in the FM system for both signal strength and center tuning, allowing for easy and accurate tuning. A directly driven LED offers immediate indication of FM stereo reception.

Low Cost AM FM Stereo Receiver

A single transistor tone control circuit was designed as the optimum cost/performance trade-off. The transistor is configured in a shunt-shunt feedback design, allowing gain variations between input functions.

The stereo power section, consisting of the LM378 dual audio amplifier, delivers 3W/channel with total harmonic distortion (THD) less than 1% and 4W/channel with THD less than 10%,

Powered USB Hub Help PC Interface

I got a strange problem as i added more and more peripherals, the pc gave odd messages, “i cannot detect what you are doing” and things like that. I almost flipped trying to locate the culprit. The problem was not in any peripheral but in the USB port powering the system itself. The SMPS was not loading much. Certainly the peripherals were drawing more and the warning could have been more like “use your own power”.  Computer Data Interface

Powered USB Hub Help PC Interface

I could not locate a powered USB with any vendor close by, so i built one and it works perfectly, Now it doubles up as a UPS Low Batter Indicator, by rare coincidence. If the Unregulated DC is above 7 volts, then no bugs. When i adjust the unregulated DC to the 7805 to around 6.9V, then i have a advance warning system.

Wireless USB – Wireless Extension to USB

USB Hub with Power

When power fails, i keep working and listening to music from a Flash Thumb drive. When music stops, i turn of computer, the lead acid batteries gone below 20 V DC. This avoids deep discharge of my batteries. The Powered USB gets undetected when the supply falls below 4.5 probably.

Bicycle Light Projects

Bicycle Light Projects

Constructing or modifying a bicycle lighting system should be done carefully to enhance the lighting and not displace a minimum lighting that is needed for safety.In rural areas and mountain bikes more lighting may be needed.

Dynamo LED light electronics – A nice selection of electronic circuits to power LEDs from a bicycle dynamo

Battery LED light electronics – A basic step-up circuit to power an LED from a battery

  • Universal single-LED headlight
  • Universal triple-LED headlight
  • Universal LED taillight mechanical construction

High-power halogen headlight

High-power halogen headlight from standard parts, battery-operated

  • Lots of light for your money
  • All standard parts, easily completed in half a day

CircuitLab – Online Schematic Editor and Simulator

Draw and print beautiful schematics for lab reports. In-browser simulations make it easy to quickly learn electronics concepts. No need to Install, it is a Online Web Application !

CircuitLab – Online Schematic Editor & Simulator

Test and Simulate circuit ideas before breadboarding. SPICE-like models with a mixed-mode simulation engine help you apply one tool to a wide range of design tasks, from digital to analog, DC to VHF and beyond.

BJT Cascoded Active-load Differential Amplifier with CMFB

BJT Cascoded Active-load Differential Amplifier with CMFB

Build non-op-amp Common-Mode Feedback (CMFB) – This kind of high-gain differential input stage might be useful as part of an op-amp, but it’s a bit silly to include an op-amp within a stage another op-amp……

Some Examples

  • 555 Timer as Oscillator / PWM Generator
  • 7805 & Wall-wart Experiencing Voltage Drop-out
  • Digital 4-bit counter and DAC
  • Diode full-wave (bridge) rectifier
  • Laplace transform step response and Bode plot
  • LED with resistor biasing
  • MOSFET switching inductive load
  • Op-Amp inverting / non-inverting amplifier
  • RLC resonance
  • Zener diode voltage reference