Octavio, I've been looking at a variety of front-ends and the one mentioned below is very similar to the Linear Tech app note. I've tried different wide-band amps following the FET buffer. I've also looked at the recent Circuit Cellar Ink article and one in Electronics Now (May 98) as well as many other circuits. All my work is very preliminary at this time. I need to finish the logic analyzer first. I've been following the discussion on using the Gameboy. I had no idea that it's architecture was open or had so many resources available. My first question is how fast can you sample data with a Gameboy? It seems that you can only do a 1-2Mhz DSO with it. If that's so, there are less sophisticated analog front-ends that would work fine. For example; one of the many FET-input op amps. You would still get a decent bandwidth and a very low input bias current. - Tom At 11:15 AM 8/12/98 -0300, Octavio Nogueira wrote: >Would you mint to share your front end with me? I'm developing a Gameboy >DSO. > >With best regards, > >Octavio >====================================================== >Octavio Nogueira - e-mail: nogueira@mandic.com.br >http://www.geocities.com/~oct_nogueira >"ProPic" Production PIC Programmer Windows under US$20 >====================================================== >-----Mensagem original----- >De: Tom Handley >Para: PICLIST@MITVMA.MIT.EDU >Data: Ter¨a-feira, Agosto 11, 1998 08:39 >Assunto: Re: Another PIC based DSO project > > >> Martin, I looked at that article and found it very interesting. For DSO >>applications, he provides a nice front-end. All I've done in that area is >>run simulations under Electronics Workbench v5.1 using vendor supplied >SPICE >>models from Analog Devices, Maxim, and Linear Technology. I'm leaning >>towards a resistive divider to scale the input instead of a PGA. I've been >>`playing' with a modified FET-input front-end from a Linear Tech app note. >>in their 1993 "Linear Applications Handbook Volume II". This is AN47; "High >>Speed Amplifier Techniques. A designer's Companion for Wideband Circuitry". >>This covers a wealth of information including the "ABC's of Probes" >>contributed by Tektronix. One application is a 100Mhz servo controlled FET >>input amp with a 10M/3pf input and 100pa bias current. In addition to the >>bandwidth, it seems to have a good DC response. >> >> - Tom >> >>At 10:20 AM 8/7/98 -0400, Martin wrote: >>> Yesterday I got my August 1998 issue of Circuit Cellar INK in the >>> mail, and it has an article and construction project that fits right >>> in with the recent discussions here about a PIC based DSO project. >>> >>> This project is an entry into the Circuit Cellar/Microchip Design 98 >>> contest, and is interesting in that it is a mixed signal analyser, >not >>> just a DSO. It combines a 50MS/s logic analyzer, and 50MS/s DSO with >>> 100 MHz vertical amplifiers (allows subsampling 100MHz signals at >>> 50MS/s), with a common trigger, allowing a digital pattern match to >>> trigger an analog trace, and vice-versa. Communication with the host >>> is via RS-232, and the host can be any of a number of platforms. The >>> control software is generic and can be ported to almost any OS and >>> hardware and the hardware is designed to allow 3rd party expansion. >>> >>> All schematics are provided, and no esoteric devices are used. Even >>> the PIC is just a lowly 16F84. >>> >>> If nothing else, this project could provide the design for stable >>> 100MHz input amplifiers. >>> >>> >>> CIAO - Martin. Tom Handley New Age Communications Since '75 before "New Age" and no one around here is waiting for UFOs...