[time-nuts] schematics of frequency counter

[Li Ang]

Charles Steinmetz <csteinmetz at ...> writes:

> 
> 
> >Actually, I dont want to ask my colledge for help. Everytime ,for 
each
> >guy I ask for help, I need expain the entire system and principle of 
a
> >frequency counter to him. They just keep asking questions instead of
> >  answering mine.
> 
> In defense of the hardware guys, there are a lot of questions that 
> NEED to be asked (and answered) before a design that fulfills your 
> requirements can even be attempted.  I don't mean to be unkind, but 
> you skipped all of those questions, designed the software, and now 
> you want someone to hand you a hardware design that solves the 
> problems you are having.  From what I can tell, you still don't even 
> have a good concept of what the hardware needs to do, much less how 
> to specify these needs as coherent project requirements -- and even 
> less how to actually design the circuitry you need.  Furthermore, 
> when someone suggests something that might fix a glaring error in 
> your design, you say you can't do that because (for example) PNP 
> transistors are too expensive.
> 
> Ask any competent engineering manager and you will learn that good 
> analog design engineers are the rarest and hardest to find 
> development team members, and that getting the hardware right is very 
> often the hardest part of any design (note that I did not say, "most 
> time-consuming" -- rather, "hardest").
> 
> So, now you need the analog hardware for your counter, and you have 
> the mistaken impression that it shouldn't be any effort at 
> all.  Hopefully, you are now beginning to understand that at least as 
> much good thinking needs to go into the hardware as into the 
> software.  And hopefully, you have reviewed the analog circuitry of 
> some good commercial designs to see what sorts of things good analog 
> designers have done in the past to solve the same problems you are 
facing.
> 
> You said yourself that you don't really know anything about analog 
> design, and your existing circuit and your comments here on the list 
> show that to be an honest and true assessment.  But you also have 
> resisted advice you have gotten from experienced analog designers, 
> and now you say you can't even be bothered to answer the questions of 
> people who would try to help you!
> 
> At this point, I'm afraid that whatever is posted on this thread 
> isn't really going to help you improve on what you have -- it is just 
> so much wasted internet bandwidth.  You need to learn at least enough 
> about analog design to ask and answer intelligent questions about 
> your needs, and you need to be willing to consider the advice you 
> receive, before any of this can help you.
> 
> Best regards,
> 
> Charles
> 
> 


Hi Charles,
   I don't mean to offend hardware guys. I've got a lot of help from 
them. The questions I am talking are something like: my 2.4G counter 
costs only 10$, why do you want to build one? Why don't you multiply 
reference clock to 400M with your FPGA as reference? Why do you need so 
many digits? It's PLL age, who needs a frequency counter? ... 
   On this list, a lot of experienced people like you have given me a 
lot of suggestions. If my words sound like resist advises I don't mean 
that. (I did say ADM7150 is too expensive and has different package that 
I can not use it now. However, I have done test of changing FPGA's 
current strength & slew rate to see if the noise of TDC power supply 
matters.)
   Because some are easy to achieve on my current board, some need to 
modify the hardware. I choose the suggestions that can be done at the 
moment. Something like PNP transistor or low noise LDO need new board to 
verify. I have got some BFT92 and looking for pin-pin compatible low 
noise LDO to play with.



Thanks

Li Ang