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Cholerny Spammer
Joined: 03 Nov 2010
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Location: England
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 Posted: Wed 14:39, 08 Dec 2010 Post subject: ghd glätteisen LCD contrast control _1051 |
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LCD contrast control
Annoying. This circuit can solve the problem. The l0 \5V supply voltage, the potentiometer itself and a 500 ~ A of additional current. Therefore, from the energy point of view, with very low energy efficiency lOkn potentiometer. Now,[link widoczny dla zalogowanych], here an integrated circuit LM334, then add a resistor, to form a constant current source. This circuit guarantees a 200 ~ A of current to ground. by a fixed resistor Rl replaced by the 3300 2.2kn the potentiometer,[link widoczny dla zalogowanych], the current can be adjusted as needed. Rl of the value can be calculated as follows : _6Rl = 227x10xT / l where T is the absolute temperature, that is KelVin temperature, and I is current, in units of security (A). the requirements of I = 200 ~ A, if the ambient temperature of 293. K, are obtained: Rl = 227x10 ~ x293 / (200 × lO) Rl = 330n note, LM334 to provide current and temperature. In fact, the current flowing from the monitor is also related to temperature, but does not require the stringent requirements of these two currents of a linear Division relationship. Even if the temperature of l0. K, the problem will not happen. for their own consumption to 1.2mA of L ? D, this circuit can save 25%. Obviously, this is a battery-powered devices fixed value. In addition, when the battery voltage drops, do not need to re-adjust the contrast. When using the new technology products, such as OLED and PLED replacement LCD,[link widoczny dla zalogowanych], the sound approach is to carefully test this circuit, first to see if can be used to adjust the brightness . Guang ± Ⅲ battery Ju electrical function of the circuit clock radio with a \scheduled cycle. This time period can be extended,[link widoczny dla zalogowanych], as long as the \, here is a simple analog timer, composed of only a few components. Press Rl Sl rapid adoption of the battery to charge on Cl, as Cl on the Tl FET gate voltage exceeds the threshold voltage, Tl guide pass, and RL connected to the battery. Here Tl is used should be effective management BSI70 field or lRL54o, the maximum load current l0om and lA. For both types of FET,[link widoczny dla zalogowanych], the source of a gate voltage drop can be neglected. maintained as long as the voltage on C1 is greater than T】 gate threshold voltage (on the icon of the FET, and its value is about 2V). Tl to continue to turn. the \The value of R2, R2 control the discharge current of Cl, the second is the capacity of capacitor Cl, while the final factor is the supply voltage from the battery BTl. When Cl is charged to high voltage, then the gate down to Tl threshold voltage of the following is also required for a long time. 16LM334 ● di circuit to the value of a component can be obtained about l0 minutes on-time (supply voltage of 5V). FET turn-off very slowly, that is, When the conduction time to time, Tl does not immediately stop, but only slowly reduced to zero, only the analog circuit load will not cause any problems, but if the load contains digital circuits, can cause instant failure. BS170lOOmAIRL54Os1RL
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