Instrumental amplifier selection for RLC meter

[liteon]

Instrumentation amplifier selection for RLC meter

Hello!
My question is about particular RLC meter in the link blow.
http://hardlock.org.ua/viewtopic.php?f=11&t=9
Its a project simple enough and seems to be having good performance.Still i need to ask if i can substitute the instrumentation amplifier originally in the schematics AD620,with AD622. The web site is in Russian and needs to be translated to understand.The author has also discussed the possible substitution to be INA128/129.I come from place where its not easy to find whatever you need.I can get AD622,looked at the datasheets for both AD620 and AD622 both are pin and function compatible but performance parameters are little different from each other(AD622 is little inferior to AD620).
I need expert opinion,please look at the schematics, how much the replacement will effect the performance of RLC meter.

Thank you very much.

 

[betwixt]

Is that design really using a switch mode supply just for the LCD backlight??? That seems like enormous overkill, especially when it has a 12V supply already available.

Brian.

 

[liteon]

well as for as i understand from the translations, most of the parts used are selected for their SMD versions. and there are 2 versions of the pcb on the page though most of the parts are through hole but one of the design used 8-pin smd chip regulators and other uses 7805 in TO-92 package. Instead of putting all of the operational load on single 7805 regulator, each section of the schematics is being equipped by its own v-regulator. MC34063 is used in step down mode just to power Back light who's power consumption may reach 50mA more than all of the other circuit collectively And is for sure beyond the safe limits of TO-92 package of 7805.There could be many reasons in the mind of original designer for using Switching regulator for this particular application. switching regulator is always way better than linear ones,in this case if the circuit has to powered by internal battery in the field instead of external 12v supply there will be less conversion losses while the back light is sucking the battery out its charge very fast.