Помогите со схемой
Пожалуйста помогите оставить схему
данное устройство представляет собой генератор тайм кода для синхронизации устройств. Описание на английском, то что все детали надо как можно ближе - тоже понял
а схему составлять - боюсь что то перепутать и подпалить детали....
вот описание
one 12.288MHz 5V crystal oscillator, for 48k word clock. Easiest to solder is DIP (such as Digi-Key part SE1733-ND) or metal can.
- one 74HCT4040, in a DIP package
- one 74HC245, in DIP.
- three 100nF ceramic capacitors.
- one 75 Ohm resistor.
- a small piece of perfboard (printed circuit board for experiments with holes on a 0.1in grid)
- a BNC connector, for the word clock cable. This should be a 75 Ohm impedance model (although a 50 Ohm model will likely work with minimal degradation)
- a 5V power source (in a pinch, 3 AA batteries will do).
Recipe:
- General: this is hi-frequency stuff. KEEP ALL WIRES AS SHORT AS POSSIBLE.
- Hint: Do a dry run on perfboard before soldering anything. See which placement allows for the shortest connections.
- Get the datasheet for your particular crystal oscillator. These invariably have four pins: one ground, one output, one VCC/+5V and one NC/OE. Ignore the last pin, you can leave it open.
- Connect all GND pins together. Close as you can!
- Connect all VCC pins together. Close as you can!
- Put a 100nF capacitor across the supply pins of each IC, with one capacitor leg to the GND pin and one capacitor leg to the VCC pin. Again, shortest wires are best. Optimal placement of the caps is likely on top of the ICs (for this step, the oscillator counts as an IC).
- Connect pin 11 of the 74HCT4040 (MR) to ground. This wire needn*t be extra-ultra-short.
- Connect the output of your crystal oscillator to pin 10 of the 74HCT4040 (/CP).
Now, the 74HCT4040 is a chained divider which divides its input signal by powers of two. We need a 48KHz word clock, this equals 12.288MHz / 256. This divisor is available at output Q7, pin 13 of the 74HCT4040. Only the *4040 doesn*t have enough oomph to drive a wordclock cable, this is where the 74HC245 comes in.
- Connect pins 2 thru 9 (A1..A8) of the 74HC245 together. Either use lots o*little jumpers ore one big blob of solder, just be careful not to overheat the part.
- Connect pins 11 thru 18 (B8..B1) of the 74HC245 together in the same way.
- Connect pin 1 (DIR) of the 74HC245 to VCC. Easiest way is to wire it to pin 20 of the 74HC245. This wire needn*t be ultra short.
- Connect pin 19 (/OE) of the 74HC245 to ground.
- Connect pin 13 of the 74HCT4040 to pins 2..9 of the 74HC245
- Connect one end of the 75 Ohm resistor to pins 11..18 of the 74HC245
- Connect the other end of the 75 Ohm resistor to the center conductor of the BNC connector.
- Connect the shell of the BNC connector to ground.
- Carefully re-check all your connections
- Apply +5V power between ground and VCC
There you go, your very own 48k word clock generator! Parts cost (without supply and case) likely less than a fiver.
Re: Помогите со схемой
Сообщение от Alex
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