Saturday, August 13, 2016

CFL Lamps and Simple Inverter

Kindly help me make one issue devoted to------ CFL Ballast Circuits----viz. circuits to drive a 5/7/9 / 11W....upto 18 watts CFL from a 6 volts / 12v DC battery, or Solar Panel,(or 220 volts AC Mains) Believe me, this is a crying need ,of the day, all over.

The market is flooded with poor Lanterns, that work for 2 to 4 months then they can't be repaired even. Some makes are either high-cost/high Quality, or low cost - low quality. Custom Ballast ICs coming nowadays are no use, because they are obsolete in 4 to 6 to 12 months..

Also, the circuit must have a (SMPS) power supply too, with overcharging * under voltage cutoff, as the CFL goes black, on being switched at low voltage.

mail from SRM

I can try to help you, Please Explain your need. Which way do you want me to help you.

CFL Lamps and Simple Inverter

A simple inverter for florescent lamps
This inverter is very easy to construct, reliable, and even powerful enough to light up a 15W florescent tube (if you cool your transistor well). The only hard-to-find piece of this baby is the so-called yellow inverter transformer

Oh no! Not Another CFL Inverter
This one’s a beauty. It will drive multiple CFLs without the need for heatsinks on the MOSFETs. Fit heatsinks and you can run even more, up to a total of 100W.

I can design with some SMPS type chips. Overcharging is only in Emergency Light Lamps. CFL's do not have this as they work on 230V. Make a more detailed specification. Then I can think more about it.

delabs

the problem is NOT that simple.............. problem is to RUN a CFL bulb, from a 6v/12v DC battery. Again, the problems are-----

1)Efficiency, of energy utilization, in the battery
2)Without using Custom LSIs(which go obsolete Unavailable in 6/12 months time and are replaced constantly ,by ever more sophisticated costlier models
3)Blackening of the ends of CFL, near electrodes
4)LIFE of CFL(supposedly--12000hours for European CFLs;8000hours for Advts;5000hours maybe ,reallife...
5)Simple Circuit, which can be easily repaired in the field, by non-technical people in village/small towns.
6)Low Cost--so, even the poorest person can buy use it
7)Fast Charging , of the Battery(out of 24 hours--likely to be used for 4/6/or 8 hours .So, it has to be charged in the balance of 24 hours...
8)Low Battery High Battery Cut-off; to prevent damage to battery CFL
9)Compliance with the Basic Ignition Data, furnished by CFL manufacturers.These are like----filament voltage,Ignition Voltage, Current etc

mail from SRM

Tuesday, August 09, 2016

Binary ASK modem - Power line Modem

Want hlp in dsigning of a binary ASK modem or Power Line Modem.

Mail from AM UK


Study these links ....
Amplitude-shift keying (ASK)

Amplitude-shift keying (ASK) is a form of amplitude modulation that represents digital data as variations in the amplitude of a carrier wave. In an ASK system, the binary symbol 1 is represented by transmitting a fixed-amplitude carrier wave and fixed frequency for a bit duration of T seconds. If the signal value is 1 then the carrier signal will be transmitted; otherwise, a signal value of 0 will be transmitted.

OFDM-Based Power Line Communication Modem

"The MAX2990 power line communication (PLC) baseband modem delivers a cost-effective, reliable, half-duplex asynchronous data communication over AC or DC power lines at speeds up to 100kbps. The MAX2990 is a highly integrated system-on-chip (SoC) that combines the physical (PHY) and media access control (MAC) layers using Maxim's 16-bit MAXQ microcontroller core. The MAX2990 utilizes OFDM modulation techniques to enable robust data communication using the same electrical network that supplies power to all other devices on the network."

LEDs Allow New Remote-Controlled Lighting Applications

LEDs Allow New Remote-Controlled Lighting Applications

PLC technology allows communication over a long range. New OFDM-based PLC technology, including emerging standards such as G3-PLC™, is simplifying integration of lighting control applications by providing noise immunity and interoperability.

delabs

Wednesday, August 03, 2016

Winding Insulation Resistance Measurement

I am working in power plant. we have a problem on one of gas generator. the problem is that low winding insulation resistance of generator rotor. it read 800 k ohm where the other generator read greater than 10 M ohm. at full speed, there is no Kv measurement. same time no standing alarm from excitation system. all equipment are indicated okay.

My question is that is the relation between low isolation resistance of generator rotor and Kv measurement?

Mail from - IB SA Arabia

There is no relation between insulation resistance and any other parameter of you system. Insulation Resistance depends on age, physical damage on windings, humidity, contamination, wear and tear.
Let me know where you are doing the KV measurement. If you are measuring leakage voltage due to insulation breakdown, you have to fix it. The relationship of parameters does not matter. Small leakages can be tackled with grounding, don't compromise on safety and quality.

Dana Tekno Crossmeg Insulation Tester

Dana Tekno Crossmeg Insulation Tester

It is possible you may be touching one of the probes when you measure insulation, that may be the 800K, Even if one finger touches the probe, the circuit is closed via earth and a low 1M measurement can be seen.

The rotor the chassis all need to be grounded, and insulation resistance has to be measured after all power connections or electrical connections are removed. The electrical terminations unit should float for proper measurement, especially when you have doubts. Tell me about your progress.

delabs


I did not get a reply later, but i may not have understood the question well. The question also lacks details. In HV breakdown measurements KV is applied, but it has to be done after disconnecting all points. Beyond a limit, HV testing becomes destructive. Leakage Monitoring and Earth Leakage Breakers can be used. Motor/Generator Protection Units too. Even an imbalance in the current or Three phase problems.

It is best to use a Insulation Tester to apply little above Normal Voltage and see leakage, if this is a routine quality check. Better still, have a current sensor on the earth line and use a data logger to keep a tab on the leakage levels, temperature and voltage of all motors and generators. Even sound/vibration sensors will be an advantage. Before these electrical equipment fail many symptoms can be caught by data logging and limit windows. An electronic instrument or Trip Circuit will operate or alert after a fault occurs. Data logging and analysis will warn of a possible Motor or Generator performance degradation. Symptoms Indicate problems, prevention better than cure. Data Recording, Graphs and preemptive measures better than Breakdown Repairs in the Night. Drop in efficiency is an indicator for maintenace, This also prevents mishaps and power wastage.

It is true some insulation faults will show up on vibration and high humidity levels. These have to be simulated. In operation testing has to be done with sensors and recorders for leakage current etc. not insulation resistance.

Learn more about Insulation testing
- delabs

Tuesday, July 12, 2016

Ultra Sound Sender Detecter Diagram

I am a University Physics technical staff member and I am searching a Diagram and full detals about Ultra sound detecter (Sender & receiver & Detecter). It must be arround (Detecting range ) 1.2 MHz. This is for the student practical activities.

Pl help me if you have any information. This will be a gratefull help to the students for their studings.

Mail from PBG Sri Lanka

See an earlier post - Ultrasonic distance measurement if i find more it will be added here Ultrasound Have a look at all links below, that might help

Ultrasonic Sound

"Sounds in the range 20-100kHz are commonly used for communication and navigation by bats, dolphins, and some other species. Much higher frequencies, in the range 1-20 MHz, are used for medical ultrasound."

Ultra Sound Sensor

4QD-TEC: Ultrasonics: remote control and Intruder detector - These ultrasonic circuits are all quite old: my notes date them at mid-70s so ... The last circuit is an ultrasonic preamp with a twin T feedback to make it ...

Schematics Depot (tm) - ultrasonic switch circuit - The ultrasonic receiver circuit uses an ultrasonic receiver transducer to sense ultrasonic signals. It also uses a two-stage amplifier, a rectifier stage, ...

Silicon Chip Online - Circuit Notebook - Besides being used as a Bat Detector, the circuit could also be used as a simple tool to indicate frequency, to find tyre punctures (which emit ultrasound), ...

Ultrasonic (Ultrasound) Electronic Circuits - Ultrasonic (Ultrasound) Circuits

delabs

Sunday, July 10, 2016

Logic Analyzer on Computer

Title: Test circuit for Logic Analyzer - Message: I am a retired hobbyist. Source files needed.The following was submitted on March 8th, 2008 at 06:47AM (CST). Subject: delabs Schematic Source Request.  Circuit: del20006.pdf .
Mail from JL USA

Sorry for the late reply, Can you explain in detail your doubt or problem. Meanwhile Have a look at
these circuits

40MHz 32 Channel Logic Analyser It is a 32 Channel, 40Mhz, fully PC controlled TTL/CMOS logic analyser with internal/external triggering and trigger delay. Internal triggering is fully maskable (High/Low/Don't Care) on all 32 channels.

FPGA Based Logic Analyzer The project includes the actual analyzer in VHDL (for Spartan 3 FPGA) and a PC Software for the end user. The design employs a FPGA board that can be obtained easily.

Logic Analyzer on Computer

MiniLA - logic analyzer SW & HW.
MiniLA is a project of simple and cheap logic analyzer designed for amateur and semi-professional work.

delabs

I am interested in obtaining a copy of the file "Logic.zip" referred to in the article. PC-Based Logic Analyzer (below). The link to the file is not available. The file contains the software for the circuit described.

Reply from JL

Thursday, July 07, 2016

Understanding Transistor Power Dissipation

I like your page about current source circuit basic design. However, I still have Little confuse of the power dissipation calculation.

The max power dissipation of my circuit is 20.5V x 0.5A = 10.25W, but transistors I found are 2W power dissipation. But my input voltages is just varied from 18.0V to 20.5V only. Do you think the 2W power dissipation transistor is fine? Any help will be appreciated.

Mail From MT

When the Current source output is short circuited or connected to a low impedance load say 10 ohms, the full voltage of input 20V falls across the transistor but current is limited to 0.5A. which means the 2W transistor may Roast. The transistor when conducting, the watts is the volts across it and current thru it. Not your supply Voltage.

Power Electronics & Solar Energy

HeatSinks in Electronics

HeatSinks in Electronics - For all types of packages, there are heatsinks. They are mainly made of Black Anodized Aluminium. Aluminium is a good conductor of heat and Anodizing prevents any form of corrosion. Linear Regulated Supplies, RF Transmitters and Power Amplifiers have Devices that need heatsinks. Use Mica, Silpad, PolySulphone Pads for Electrical Isolation. HeatSink compound too.

Power Supplies Section

Design in such a way there is no short circuit or a a power resistor in source. But then efficiency drops. The best way is to use a switching supply design or keep the input voltage across transistor to a minimum.

delabs

Saturday, June 11, 2016

SSR Open Circuit Leakage Voltage

hi been trying to use a dc ssr relay to switch 24 volt supply on and off for a unit i use that needs to see 0v or 24v but when the switch voltage is applied there is still 18v showing on the load side not zero ..does the ssr have to have a load on it to fully switch off and on from 0v to 24v ?

Mail from PST in UK


You are right you need a bleeder resistor of 10k or 100k to ensure the collector leakage current of SSR is bypassed to make you see a '0' when the SSR is off. If the SSR is working well, and no input or '0' control input then SSR output is high impedance and only a collector or diode leakage will hold the SSR output at the Full Voltage but it cannot drive any current. Hence a bleeder across output will show you a '0'. Use it if the bleeder does not cause any problems.

Solid State Relays or SSR

If you were driving a 5A Solenoid, then you would not see this problem. If you are driving a Solid State Load, such effects are natural. It is because the Solid State Load like a Electronic Circuit will draw current only on demand.

These instruction is for a Normally Open Output, NO. A Normally Closed NC is vice versa. And also some Special SSRs may have sensitive inputs, So a low impedance '0v' at input has to be ensured.

The Bleeder should bypass the leakage current, so one end of bleeder goes to SSR output and other end of bleeder goes to the ground or 0V point of your circuit which is controlled by SSR.

delabs

They are called SSR as there are made of semiconductors and have no moving parts to wear out. They do generate heat depending on load and switching. Thyristors are used in most as they are rugged, mosfets and IGBT may also be used for various applications.

Solid State Relays or SSR

 In this section you will find SSR designs and PCB layouts which you can study. These were made and sold  by me years ago. So the PCB layouts have gone thru some revisions and they worked quite well.