Simple High speed data switch

 Digital-Circuits, Discrete-Circuits  No Responses »
May 162005
 


This circuit is a small representation of a very low cost printer sharer i made very long ago. This is as much i can remember of the basic ideas behind the product.

Simple High speed data switch

I used to pot the product in epoxy with a black dye and sold a few, they sort of served the purpose. Output impedance of this circuit is high, sink is 220K source is 3.9K+ so use some buffers or drivers at Output.

when Enable A is at float-high impedance or low the output O1-O4 is not influenced by A1-A4 inputs. If Enable A is made logic high or 5V then A1-A4 is available at O1-O4.

By turning Enable A or Enable B high, you can route the data A1-A4 or B1-B4 to the output O1-O4, you can also mix data and you can expand to any number of input sets or data width. 1N4148 is fast, 4nS, that makes this data switch quite fast. This circuit cannot drive long printer cables without drivers. They will load the output.

 Posted by admin at 6:01 PM

5V -1A Power Supply using LM2575

 Power-Supplies  No Responses »
May 032005
 
5V -1A Power Supply using LM2575

A Power Transistor which is having a drop of 4 Volts across it and passing 3 amps thru it, may dissipate around 12 Watts of Heat, This is the problem in Series Regulators. While a Saturated Transistor or Mosfet with 1 Volts across and 3 Amps Thru will be just 3 Watts. But then a fully on transistor or mosfet cannot be controlled or regulated, for that we turn it ON and OFF very fast so that the right amount of current or voltage is delivered. The way this is done is PWM – Pulse Width Modulation. In this the Read More …

 Posted by admin at 7:06 AM  Tagged with:

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
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