i post it here but i DO NOT recommend you waste your time and resources attempting to build it *** - just for the principles of the ADC . . . the ADC are built into MCU-s and are avail at the variety of types -- having better accuracy , speed-characteristics and are likely more efficient and noise proof (if the PCB layout is done rigth ...)
so the ADC using digital inverting gates they are tripled here for the reason that the '04 have barely any hysteresis but are sensitive to input signal + '14 (a Schmitt inverter) has better output drive capability for analog resistor summing networks
(the principial simulation) ... has the drawback that the output is not changing simultaneously but delayed from MSB to LSB
(the simulation with a buffered OUTP) assumes relatively smooth (≈ static and flicker free) INP signal --e.g.-- it has barely any practical*** use
i passed a slight error to the pre-prev. HC04/14 ADC -- the offset of the MSB should be summed to V.th (input threshold voltage) at Vinp = Vdd/2 also ...
the simulators suggest that it's (Vth) couple of tens of mV above the Vdd/2 (the supply median) ... so the Vinp should be "pulled up" a bit ...
the approximate inner workings of the HC04/14 :: the 74HC04 oscillator versus the 74HC04 oscillator (i have not build these in real -- the Simulators can't be always nor 100% trusted . . . as they are simplified mathematical models of reality)
something i forgot ... the mosfets in Falstad (links in prev post) are apx. matched those of the CD4007 with the exception that the last.. (output/inverting stage) ..of the HC14 has them in avg. some 6x more powerful
there are typo in prev. post the second link should read "the 74HC14 osc."
---- ireelevant ::
the Blogger provides Delete not Edit option (thus supports "trashing" the "public web space" with corrective notices ((versus delete rewrite (copy/paste from the page src.) your post)))
we have had the web around about 50 years ... and still "they" don't know what and how to do with it . . . most annoying are the (mostly impractical auto completes ... that you most always have to fix)
the human is only good at one thing wasting other people time or making their life more complex
about the "i passed a slight error to the pre-prev. HC04/14 ADC -- the offset of the MSB should be summed to V.th (input threshold voltage) at Vinp = Vdd/2 also ..."
i actually planned it for the Ampere meter replacement for the PbSO₄ charger - with no much precision in mind
actually if we like to pinch an accuracy out of it there will be source of errors
► individual input threshold voltages for each "stage" (1/6x SN74HC04) ► R.DS.ON for individual outputs (1/6x 74HC14) - both upper-/lower shoulder (P-MOS , N-MOS) ► input voltage needs to be buffered with a powerful near R2R Op-Amp as MC33071 , NE5534 , etc. ...
however the simulated threshold's offset is about tens of mV -s while the bit step 5/15 ≈ 333mV 39mV/333mV about 12%
anyway since all inputs require the level-shift it's better replace the first inverter in '04'04'14 with the inverting comparator
the cheap comparator LM393 usually has propagation delay about 1µs . . . means the input must be in steady 333mV window for the sample/conversion (A→D) to be near valid
e.g the design is still only good for slow changing input and when relatively low output precision is acceptable
the Falstad simulation of the LM339 variant of the above ADC (without the 74HC04 - a "boosting stage" for non-analog discrete logic ... the LM339 is fast but in non-inverting configuration - that is just a bit slower*** than the inverting configuration . . . maybe - applies for op-amps . . . the comparator is just few steps away from op-amp ... all the op-amp models and comparator models are different ... so the ***feature needs to be verified for a particular model - if its a significant benefit or not)
FYI :: there are inconsistency on your invoice HC is TTL compatible but listed is TTL family ID -- if it's ok with you don't bother the shop -- otherwise in today's fast changing labor market -- you must know :: • what you buy • from where you buy • what's the normal price for the item (@ where you buy it from)
7 則留言:
i post it here but i DO NOT recommend you waste your time and resources attempting to build it *** - just for the principles of the ADC . . . the ADC are built into MCU-s and are avail at the variety of types -- having better accuracy , speed-characteristics and are likely more efficient and noise proof (if the PCB layout is done rigth ...)
so the ADC using digital inverting gates
they are tripled here for the reason that the '04 have barely any hysteresis but are sensitive to input signal + '14 (a Schmitt inverter) has better output drive capability for analog resistor summing networks
(the principial simulation) ... has the drawback that the output is not changing simultaneously but delayed from MSB to LSB
(the simulation with a buffered OUTP) assumes relatively smooth (≈ static and flicker free) INP signal --e.g.-- it has barely any practical*** use
see also https://www.falstad.com/circuit/circuitjs.html MENU ► Circuits ► Analog/Digital
i passed a slight error to the pre-prev. HC04/14 ADC -- the offset of the MSB should be summed to V.th (input threshold voltage) at Vinp = Vdd/2 also ...
the simulators suggest that it's (Vth) couple of tens of mV above the Vdd/2 (the supply median) ... so the Vinp should be "pulled up" a bit ...
the approximate inner workings of the HC04/14 ::
the 74HC04 oscillator versus the 74HC04 oscillator
(i have not build these in real -- the Simulators can't be always nor 100% trusted . . . as they are simplified mathematical models of reality)
something i forgot ... the mosfets in Falstad (links in prev post) are apx. matched those of the CD4007 with the exception that the last.. (output/inverting stage) ..of the HC14 has them in avg. some 6x more powerful
there are typo in prev. post the second link should read "the 74HC14 osc."
----
ireelevant ::
the Blogger provides Delete not Edit option (thus supports "trashing" the "public web space" with corrective notices ((versus delete rewrite (copy/paste from the page src.) your post)))
we have had the web around about 50 years ... and still "they" don't know what and how to do with it . . . most annoying are the (mostly impractical auto completes ... that you most always have to fix)
the human is only good at one thing wasting other people time or making their life more complex
about the "i passed a slight error to the pre-prev. HC04/14 ADC -- the offset of the MSB should be summed to V.th (input threshold voltage) at Vinp = Vdd/2 also ..."
i actually planned it for the Ampere meter replacement for the PbSO₄ charger - with no much precision in mind
actually if we like to pinch an accuracy out of it there will be source of errors
► individual input threshold voltages for each "stage" (1/6x SN74HC04)
► R.DS.ON for individual outputs (1/6x 74HC14) - both upper-/lower shoulder (P-MOS , N-MOS)
► input voltage needs to be buffered with a powerful near R2R Op-Amp as MC33071 , NE5534 , etc. ...
however the simulated threshold's offset is about tens of mV -s while the bit step 5/15 ≈ 333mV 39mV/333mV about 12%
anyway since all inputs require the level-shift it's better replace the first inverter in '04'04'14 with the inverting comparator
the cheap comparator LM393 usually has propagation delay about 1µs . . . means the input must be in steady 333mV window for the sample/conversion (A→D) to be near valid
e.g the design is still only good for slow changing input and when relatively low output precision is acceptable
the Falstad simulation of the LM339 variant of the above ADC (without the 74HC04 - a "boosting stage" for non-analog discrete logic ... the LM339 is fast but in non-inverting configuration - that is just a bit slower*** than the inverting configuration . . . maybe - applies for op-amps . . . the comparator is just few steps away from op-amp ... all the op-amp models and comparator models are different ... so the ***feature needs to be verified for a particular model - if its a significant benefit or not)
FYI :: there are inconsistency on your invoice HC is TTL compatible but listed is TTL family ID -- if it's ok with you don't bother the shop -- otherwise in today's fast changing labor market -- you must know ::
• what you buy
• from where you buy
• what's the normal price for the item (@ where you buy it from)
about logic families / (inter-)compatibility ::
Logic family - Wikipedia
Logic Guide PDF by Ti(/NS)
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