First, the circuit design
A nickel-metal hydride battery has a voltage of only 1.2V, while a super-bright LED requires an operating voltage of 3.3V or more to ensure sufficient brightness. therefore. It is necessary to try to raise the voltage. Common boost circuits generally have two forms, namely a high frequency oscillating circuit and an electromagnetic induction boost circuit. For the boost circuit, there are two circuit options. As shown in Figure 1 and Figure 2.
The circuit of Figure 1 uses a small pulse transformer. The power tube VT3 amplifies the high-frequency oscillation signal and adds it to the L1 to directly boost the voltage through the transformer T.
Figure 2 shows the use of the self-inductive high voltage of the inductor to achieve voltage boosting. When the oscillating signal is input to the base of VT3, VT3 will periodically saturate and turn off. When saturated, the inductor L is energized, and the electrical energy is converted into magnetic energy stored in L. At this time, the diode is turned off, and the energy stored by C3 is supplied to the load; when VT3 is turned off. The inductor will produce a self-induced electromotive force that is positively negative. The diode VD is turned on, and the self-induced electromotive force is superimposed with the power electromotive force to charge the capacitor C3 and the load, since the two electromotive forces are in series. A voltage higher than the power supply can be obtained, and the specific size is mainly determined by the ratio of the load and the current through which the inductor L passes when VT3 is saturated.
Both circuits can raise 1.2V to above 3.3V. The first circuit adds a positive feedback coil to the transformer. The oscillating circuit can be eliminated. Make the circuit more concise. But using this circuit is more complicated to calculate. The output power is difficult to adjust, and the winding of the transformer is also somewhat troublesome. The second type requires only a small inductor. There is no large requirement for the inductance. By adjusting the drive current of the inductor, the output voltage can be easily adjusted. The second circuit is used here.
The oscillating circuit adopts the circuit shown in Fig. 3. Although there are many oscillating circuits that can work normally under the voltage of 1.2V, it has been proved by practice that the circuit of Fig. 3 is easy to manufacture and simple to calculate. The success rate is high. The oscillation frequency is also easy to determine. and. By adjusting the size of R4, the amplitude of the signal can be adjusted without affecting the signal frequency. Therefore, this circuit is used to generate a high-frequency square wave pulse to prepare the booster circuit. In this way, the circuit design is completed, which is composed of FIG. 2 and FIG.
Second, the calculation parameters
Regarding the calculation of circuit parameters, the key lies in power. After the inductor is energized, the stored energy is E=LI2/2, let f be the square wave frequency, and the switch tube will be turned on f times in 1a. The energy stored by the inductor per second is W=f×E, and the efficiency of these energy conversion to the load is η, then the output power is P=η×W+Po, and Po is the power that the power supply directly supplies to the load (because the power supply and the self Sense of high pressure superposition. This must be considered).
Estimate now. Driving an LED is about 100mW. The Po of the power supply is approximately 20mW. In order to guarantee the supply, it is calculated as P=100mW. Take η=80%, and then find a few hundred uH of inductance, such as 500 uH: on the other hand, according to energy conservation. 3.3V is about 3 times 1.2V. Again due to efficiency issues. The drive current of the inductor is about 3-4 times the operating current of the LED, which is taken as 120mA. It can be calculated that the oscillation frequency is about 34 kHz, so that R = 2 kΩ and C = 0.01 uF can be achieved. When determining parameters. The frequency can be high or low, and the inductance should not be small, so as to ensure that the output power is large enough to have enough adjustment space.
Component table
Third, the production is simple due to the circuit. The components are on a 2 x 2 cm plate. As long as the operation is correct, the power supply circuit can work. Do not connect the LED first, and measure the output voltage with a multimeter. At this time, adjust the size of R4. The larger R4 is, the smaller the output voltage is. Vice versa, when the output voltage is about 3.2V, you can connect the LED, and then adjust the size of R4 to make it bright enough. Note that the voltage across the LED should not exceed 3.6V, otherwise the LED may be burnt. In this way, the circuit is debugged.
Find in Bescon the Casino-Style, Heavyweight 13.5-gram, Imprinted Clay Poker Chips!
Clay Poker Chip is heavier than plastic one. Usually at weight 13.5Gram with metal inserted. Modern clay chips are a composition of materials more durable than clay alone. And they are more expensive than plastic chips.
For custom clay chips we do imprinting directly on chips, or custom PVC sticker on chips.
Clay Poker Chip
Clay Poker Chip Set,Casino Clay Poker Chip,Custom Clay Poker Chip,Sticker Clay Poker Chips
BESCON INDUSTRIAL CO., LIMITED , https://www.besconcn.com