Reducing L200 Power Dissipation using Series Resistor

It’s good to reduce the power dissipated by the device. Using resistor connected in series to the input (the left figure) is a simple and economic method to reduce the device input-output differential voltage. Here’s the formula for calculating R: R= [Vi min- (Vo+Vdrop)]/Io Vdrop = minimum differential voltage between the input and the output of the device at current […]

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Switchstart Ballast Circuit for Fluorescent Tube Lamp

Simplicity, low cost and improved efficiency when compared with the alternative options are the reasons why the switchstart circuit has been widely adopted. Moreover, the 230V mains voltage is sufficiently higher than tube running voltage to let the use of the simple series impedance ballast in almost every case. Where the mains voltage is not high enough, for example in […]

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4-Channel Commutator

To reach low channel ON resistance (<30 Ohm) and low OFF current leakage, 4-channel commutator uses the 2N4091. The DM7800 voltage translator is a monolithic device. This device give us +10V to -20V gate drive to the JFETs while at the same time giving DTL-TTL logic compatibility. Here’s the circuit diagram: [Source: National Semiconductor Application Note]

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