Edison Bulb Life Extender

 Discrete-Circuits, Mains-Power  No Responses »
May 022005
 
Edison Bulb Life Extender

The Edsion Filament lamp may be less popular, but it is the most cost-effective light even today. It is very affordable, The light is soothing to the eyes and best of all gives a warm feeling. Sometimes due to the mains being restored when bulb is on, or a rapid flick of switch, blows it. This may be due to the cold filament resistance which is low, allowing a huge inrush current. The problem can be solved with a soft start based on thyristor or mosfet using PWM etc. The circuit here is a low cost solution which may help Read More …

 Posted by admin at 8:06 PM

Mains Voltage monitor using LM3914

 LED-Circuits, Mains-Power, Test-Measurement  No Responses »
May 022005
 
Mains Voltage monitor using LM3914

This Circuit helps in the monitoring of mains supply voltage. It does not use a isolation step down transformer. This has to be constructed only by skilled people with knowledge of safety requirements. C1 limits the current and drops most of the voltage. The zener regulated supply is for the chip. C2 can be raised to 220uF or more if required. The bar mode display may consume more power. R2-R3-R5-R6 form a voltage divider to get a sample of the input voltage, D11-C3 get the DC value. Adjust R5 preset with a log Plastic tweaker to get the 5th led Read More …

 Posted by admin at 8:05 PM

Simple Mains Voltage monitor

 LED-Circuits, Mains-Power, Opamp-Circuits  No Responses »
May 022005
 
Simple Mains Voltage monitor

This Circuit helps in the monitoring of mains supply voltage. It does not use a isolation step down transformer. This has to be constructed only by skilled people with knowledge of safety requirements. C1 0.47uF can be brought down to 0.22uF for low LED currents, use high efficiency ultra bright LEDs.C1 should be 440V AC or 630V DC plastic axial yellow, polyester, polycarbonate, polypropylene, metalized film. R3-R6-R9-R14-R18 resistor divider determines the LED turn on or threshold switch points, 10M for hysteresis. Adjust R16 preset with a log Plastic tweaker to get the led D2 to turn on when input voltage Read More …

 Posted by admin at 8:04 PM

Mains Current Indicator with a LED

 Discrete-Circuits, LED-Circuits, Mains-Power  No Responses »
Nov 302004
 
Mains Current Indicator with a LED

This is a mains 230V AC load current indicator and is a LIVE CIRCUIT, so take care. The Resistors have to be a fusible ceramic wire wound. This circuit has been drawn from my memory and i have not tried it out again, just see if it is ok and then try. You should use the fuse of 1A a slow blow if you want but it is very important. You can design the shunt R3 and Fuse rating as required by your load. Note that this circuit is to be put in series with the load like an ammeter. Read More …

 Posted by admin at 2:47 AM

Mains Voltage Indicator with a LED

 Discrete-Circuits, LED-Circuits, Mains-Power  No Responses »
Nov 302004
 
Mains Voltage Indicator with a LED

This is a mains 230V AC voltage indicator and is a LIVE CIRCUIT, so take care. The Resistor has to be a fusible ceramic wire wound and the capacitor 630V AC or higher capacity. This circuit has been drawn from my memory and i have not tried it out again, just see if it is ok and then try. You should use the fuse of 100mA a slow blow if you want but it is very important. This circuit has to be enclosed in a plastic sealed enclosure to avoid contact.

 Posted by admin at 2:46 AM

Solid State Relay – Common

 Mains-Power, Solid-State-Relay  No Responses »
Oct 282004
 
Solid State Relay - Common

This is a DC controlled Solid State Relay which can turn 230V AC equipment on and off. The output is like a NO normally open contacts of a relay and have to be in series with the Load like any other switch. This should not be used for large inductive loads like big motors. The Q1 transistor limits the current thru the LED by providing an alternate path for more current. The DC input can be from 3V to 20V. The Triac can be chosen depending on current in the load. Look for datasheets and applications at STMicroelectronics for BTA41600 Read More …

 Posted by admin at 7:38 PM  Tagged with:

Triac based Lamp Dimmer power control

 Mains-Power  1 Response »
Oct 262004
 
Triac based Lamp Dimmer power control

This is a phase angle control of a Triac which is a evolution from an SCR. The 50 Hz or 60 Hz Sine wave of mains can be turned on at any point after the Zero Crossing The Voltage ramps up in the sine wave which gives a near “Linear” slope which can be used to trigger the ON at a time delay after zero crossing when the voltage is zero. This is like a PWM but works on low frequency only. Some of the early SMPS(HV for TV and Mains Inverter) by Siemens were built around SCRs. Turning off Read More …

 Posted by admin at 8:34 AM  Tagged with:
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