| ??? 01/08/06 01:26 Read: times |
#106819 - Take care... Responding to: ???'s previous message |
Farshid said:
So you say i can feed this signal to a simple fast Logic gate (Like an 74HC ?) and then e.g. connect it to my MCU ,right ? Don't forget the two 47kOhm resistors at input. 74AHC86 is very similar to a HCMOS-chip. It's 'advanced HCMOS'. Well, I haven't designed this circuit, so I cannot say, why the guys have used a 74AHC86. And I cannot say, whether this trigger circuit works properly or not. Only thing I know is, that the trigger circuit is the most important part of such a storage scope... Farshid said:
The exact Op-Amps used in the circuit is not availabe here , I'll try to search for a good Op-Amp with these Specifications :
BW ~100 Mhz SR 75 V/uS JFet high impedance Inputs To find a suited OPamp is really difficult! You need an OPamp, which shows the same proper performance as MAX477. Means, a bandwidth of 300MHz, a slew rate of 1100V/µsec, a voltage feedback topology and, important, a high input impedance of 1MOhm! Providing this speed seems ridiculous, at first sight, as an analog bandwidth of only 20MHz is wanted. But take care, the OPamp needs lots of headroom to handle these 20MHz signals correctly and for this a high bandwidth of OPamp is needed! Kai |
