 |
PM |  | |
Quote | | |
Reply | | |
Full Topic | |
| Joined: | Mar 3rd, 2008 |
| Location: | Muskogee, Oklahoma USA |
| Posts: | 349 |
| Status: |
Offline
|
I'm happy enough that the idea has received a warm reception..so now on to the testing and refinement.
The transducer and even op-amp gain stage are things still quite new to myself, but I do bury my head in specsheets and datasheets most days lately. It shows 2 electronics folks now have the thoughts rounded out for improvements and I appreciate these pointers.
I've tended to build such things on my own and from reading up and 'being given' certain pointers and solutions from I know not where...though as I say, i'm not really a mystical person, but some of these links are proving to be awesome. Haar indeed !
A friend dropped off 2 boxes of misc electronics boards the other day, so I could rip stuff from them and return what I don't need, as a swap for 3 Eproms he was in need of. I have 741's, LM380's and other 8 legged wonders now, so any idea should be able to be built.
I read about stair stepping for maximising gain, but was really of thoughts of keeping all voltages to the quite small 3V. Is such a thing possible and still get good gain ?
There seems to be a starting voltage of 12V on many online op-amp circuits and quite often it can run up to 30V. The saving grace of such a low operating voltage in the unit is that headphone output has been chosen.
Battery drain isn't too much of an issue, for a couple of reasons. I can just plug it in and have current draw managed by a fitted switch to use the amp stage. The batteries are rechargeable and would face perhaps 2hrs use in a general investigation, which may offset requirements worries that way. Perhaps a ramping is possible to feed the op-amp section, if needed. It's another area of unfamiliarity.
I do still have troubles with ceramic disc capacitors though and I usually take a look on Google to see an example rating. Looks like using a multimeter, as the markings don't seem to relate to values.
Hence, from this rambling, I never wish to appear as though any idea is better than any other..I just might not understand one at first and may have had troubles building similar in the past! lol. Once I get my Visa process finished to live and work in the USA, i'll be looking at electronics study courses.
Temperature compensation is an important area. To self calibrate should be a cause and effect and I can envisage quite a simple stage for that. Along the lines of decreasing resistance giving increasing gain. It was only the other day that I realised a hair can stretch..so again, all new stuff. In bitterly cold conditions the hair would contract, yet not break because of the elasticity, so the method needs a starting referance point at each switch on. If something can 'listen' for a certain base tone and adjust itself til that tone is met, then that would be one method. Would a comparator chip like the LM339N work there ?
Again, many thanks