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HT2811 Datasheet PDF
The reply was unsigned and the author of the circuit is unknown. The sheet also shows the need htt2811 a buffer resistor on the output. There are many ways to design the circuit to get the same output. The need for the 10k resistor R1 is unknown.
It serves NO purpose. The need for the 10k resistor R4 is unknown dahasheet the op-amp pulls low. You will not know unless you wire and check yourself.
What sort of answer is this? Gates N2 and N3 are not needed as they simply produce the same result as the output of N1.
Not in this case.
N2 and N3 gates are needed, there are reasons behind it. The 22E 22R resistor R5 is far too low. The CD can source 10mA datasueet to deliver this current to the 2v2 zener requires a R resistor. You have no idea why we use these values. Your doubt is based on theoretical observations. The reason why the. One mistake led to another. The output of the BT requires a buffer resistor on the output of about 1k. The IC should not be connected directly to the base of a transistor. See the data sheet. The output current of BT is less than 2mA.
HTD PDF Datasheet, Equivalent part search
You don’t need a buffer resistor at its output pin in this design. We have the datasheet of BT The data sheet clearly shows a 5k to 10k resistor on the output. OK you say so. We have not seen or used BT Normally we used transistors symbols either npn or pnp irrespective of Darlington or not. But your point is noted. The BT can be supplied with 3v and it may be necessary to deliver 3v to drive a Darlington transistor. There is no current limiting resistor on the collector of the BC The value of R6 is technically too low.
It should be 10k. Your doubt is based on theoretical observation. The design is working fine and no changes are required. The circuit may be “working fine” but it has so many technical faults that it is obvious the designer of the datasheeet has no technical ability AT ALL. This would be ok if he just produced the circuit for himself, but it is being presented in an electronics magazine for thousands of readers to study and fatasheet and it should be technically correct.
The ROM has words and can store upto two melodies with double sound sources. It works between volts and ideal voltage is between 2. Its output cannot drive a speaker directly, so a transistor amplifier is needed. This circuit uses a synthesized sound chip from Holtek, the HT This reproduces the sound of a “ding-dong” chiming doorbell.
The operating voltage must remain within 2. The reset switch zeroes the count,and the 7 segment display is a common ht28811 type. To save power consumption the display can be enabled or disabled with a switch as shown in the above diagram. The count will still be held in memory.
The IC pin out for the is shown in pin order below:. The envelope of the chime is set by the k, k, dataasheet and 4u7 resistors and capacitors. These values are the manufactures default values, but may be adjusted to alter the length and delay of the chime.
The combination of the 2k2, 22k and 47u resistor capacitor network has a double function. It provides a debouncing circuit for the bell press and at the same time has a sufficiently long time constant. This ensures that anyone rapidly pressing the doorbell switch, only advances the count once.
The 47u capacitor may be increased in size, if needed. The count may be expanded for ht281 to 99 visits by cascading two CMOS IC’s and using an additional 7 segment display.
Explore Circuits – Doorbell
This simple and cost-effective ding dong electronic doorbell circuit is based on IC The IC has an in-built circuitry to produce ding dong sound each time its pin 3 is pulled low. Therefore a complementary-pair, two-transistor amplifier is used to amplify the sound to a datashwet level of audiblity.
You may either use a piezo tweeter or an 8-ohm, mW speaker at the output. This simple electronic doorbell has not been tested. During the standby period, the IC consumes nominal current of a few microamperes only.
Xatasheet switch S1 may be kept closed. Each time switch S2 is pressed, ding dong sound is produced twice. If you try to press switch S2 a second time when the first ding dong sound is still being produed, it has no effect whatever and the two ding-dong bell sounds will be invariably produced. Sometime it happen that sound from the IC is very slow and you are not able to hear it properly because of various kind of noise around your home or offices. This will amplify the musical sound so that you can hear it properly and from distance also.
The IR detector circuit in principle, converts the IR signal pulse trains into datashwet aural notes. Resistor R4 and zener diode ZD2 form a low-current voltage stabiliser for providing steady 5. IR LED1 is the main sensing element. The amplified signal is fed to the melody generator via resistor R5.
The loudspeaker sounds to indicate the presence of IR signal near the circuit. The IC pin out for the is shown in pin order below: Circuit lab, diagrams,Free circuits. My Electronics Projects – Tripod. Electronics Circuits, Electronics Projects list. Electronics Project Design References and Tips. Top 25 Electrical Mini Projects. Simple electronics projects and circuits. Dick Cappels’ Project Pages.