To
Charles Bannister,
Dear Sir,
I regret if my weak english has damaged the relation;I hasten to inform that from the posting here I have developed very high regard on your goodself.
There will always be ‘design tension’.My intension is actually to raise the issue of “Experience versus modern management techniques”, and learn how to compromise.
A known enemy is better than unknown enemy EQU Experience.
Lie-Damm Lie-Statistics-parts count is proportional to failure rate EQU modern management technic.
Charles Bannister, you would think the 74LS174 and 74LS08 would be more reliable than another 89C2051 .This you are sure from your experience where as one of “design’s” objective function is to reduce parts count which you defy.I am suggesting a statistically better design approach which is also known to be reliable by many (may be including you yourself in some other occasion).
I am not expecting Nobel by asking this to FORUM that should we weigh
U7 74LS174 and U9 74LS08 + U10 CD4061+ U12 CD4066 versus 2x2051
Which side is heavier? Also consider
1) 15*2=30 I/O for future unforeseens.
2) one place you can measure this voltage (P1.1) Now you have two (P1.1)s.
3) Your current probe probably better known as tong tester in my part of the world and sure it is isolated from mains.But have you touched across the meter coil movement standing barefoot on ground?How can it be isolated?O.K. in the Simpson you may not get a nasty shock.May be your ‘I MEG’s are making it behave like neon testers.I only wonder whether CE type authorities approve it under plastic casings.
4) 5000µF for reliability.50000µF for more? How do you calculate.Any refernce?
5) I note you prefer 1N4001 to 1N4007 although price and size are same but rating…..
6) You have written” If I were to use a Bridge rectifier I would require a center Tap transformer. “ Are you sure ?I think on the contrary.
7) D6:
“It prevents the battery from feeding voltage into the 7806 “:
Battery voltage minus D5 drop should not leak through 7806.Normally such regulators are protected form loads (battery or loads like yours with large capacitors) are protected,in the event of power failure by a anti-parallel lN4007 across the regulator.
8) “50 milli Volts Full Scale Deflection “: Thank you.Perhaps Andy can help in finding a more standard form than ‘50MVFS’.
9) “I guess it will seek its own level eventually. “:! That was height of it .
10) EFY is www.electronicsforyou.com.
“Start another thread sharing your experiences and ask your questions. “: You see ,on above subjects,I have experience to share.But during the decades I spent learning analogue without help of Internet, others learnt microcontrollers.I have to do a lot of homework and spadework before a proper question is framed.O.K. for the time being I quote from Atmel
“A microcontroller output (pin 11), which swings from approximately ground to V CC , alternately charges and dis-charges the capacitor connected to the non-inverting input of the internal com-parator
(pin 12). The microcontroller measures the time required for the volt-age
on the capacitor to match the unknown voltage applied to the inverting
input of the internal comparator (pin 13). The unknown voltage is a function of the measured time.”: I question is on the word ‘approximately’.What are values?Do you think it’s worth a thread?

Best Regards
A.S.Rudra