It looks to me like it is being used as an RF mixer or modulator, consideri= ng the tuned circuit in the collector circuit. A bit rough and crude maybe, but presumably works. > -----Original Message----- > From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf > Of David VanHorn > Sent: 29 September 2016 13:07 > To: Microcontroller discussion list - Public. > Subject: Re: [EE] Long tailed pair, sort of. >=20 > Yes >=20 > On Sep 29, 2016 2:20 AM, "Richard Prosser" wrote: >=20 > > Hi David, > > Silly question, where is the output. TP18 ??? > > > > RP > > > > On 29 September 2016 at 10:55, Van Horn, David > > wrote: > > > Like this > > > > > > -----Original Message----- > > > From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On > > Behalf Of Jason White > > > Sent: Wednesday, September 28, 2016 11:25 AM > > > To: Microcontroller discussion list - Public. > > > Subject: Re: [EE] Long tailed pair, sort of. > > > > > > Just out of curiosity, could you post a schematic? It might help to > > > see > > it in context. > > > > > > On Wed, Sep 28, 2016 at 10:02 AM, Van Horn, David < david.vanhorn@ > > backcountryaccess.com> wrote: > > > > > >> Possible. I googled that and didn't see anything other than > > >> differentials though, with one collector tied high. > > >> It's an odd configuration. > > >> > > >> -----Original Message----- > > >> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On > > >> Behalf Of Sean Breheny > > >> Sent: Thursday, September 22, 2016 5:44 PM > > >> To: Microcontroller discussion list - Public. > > >> Subject: Re: [EE] Long tailed pair, sort of. > > >> > > >> Could it be a two-input inverting summing amplifier? It is too > > >> symmetrical to be a differential amplifier. > > >> > > >> On Tue, Sep 20, 2016 at 12:27 AM, David VanHorn > > >> > > >> wrote: > > >> > > >> > It's supposed to be a differential amplifier, but I don't think > > >> > it's > > >> right. > > >> > > > >> > On Mon, Sep 19, 2016 at 9:30 PM, Jean-Paul Louis > > >> > > > >> wrote: > > >> > > > >> > > NAND gate using RTL logic? > > >> > > > > >> > > Jean-Paul > > >> > > N1JPL > > >> > > > > >> > > > > >> > > > On Sep 19, 2016, at 6:07 PM, Van Horn, David > >> > > backcountryaccess.com> wrote: > > >> > > > > > >> > > > I am looking at an amplifier, which is almost a classic long > > >> > > > tailed > > >> > pair > > >> > > as figure 2 here: > > >> > > https://en.wikipedia.org/wiki/Differential_amplifier > > >> > > > > > >> > > > The difference is that there is only one collector resistor, > > >> > > > and both > > >> > > collectors are tied together. > > >> > > > What's up with that? > > >> > > > > > >> > > > I haven't seen that configuration in Horowitz and Hill or Ghau= si. > > >> > > > > > >> > > > > > >> > > > -- > > >> > > > David VanHorn > > >> > > > Lead Hardware Engineer > > >> > > > > > >> > > > Backcountry Access, Inc. > > >> > > > 2820 Wilderness Pl, Unit H > > >> > > > Boulder, CO 80301 USA > > >> > > > phone: 303-417-1345 x110 > > >> > > > email: > > >> > > > david.vanhorn@backcountryaccess.com > >> > > backcountryaccess.com> > > >> > > > > > >> > > > -- > > >> > > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list > > >> > > > archive View/change your membership options at > > >> > > > http://mailman.mit.edu/mailman/listinfo/piclist > > >> > > > > >> > > > > >> > > > > >> > > Just my $0.02, > > >> > > > > >> > > Jean-Paul > > >> > > N1JPL > > >> > > > > >> > > > > >> > > > > >> > > > > >> > > -- > > >> > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list > > >> > > archive View/change your membership options at > > >> > > http://mailman.mit.edu/mailman/listinfo/piclist > > >> > > > > >> > -- > > >> > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > >> > View/change your membership options at > > >> > http://mailman.mit.edu/mailman/listinfo/piclist > > >> > > > >> -- > > >> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > >> View/change your membership options at http://mailman.mit.edu/ > > >> mailman/listinfo/piclist > > >> > > >> -- > > >> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > >> View/change your membership options at > > >> http://mailman.mit.edu/mailman/listinfo/piclist > > >> > > > > > > > > > > > > -- > > > Jason White > > > -- > > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > View/change your membership options at http://mailman.mit.edu/ > > mailman/listinfo/piclist > > > > > > -- > > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > > View/change your membership options at > > > http://mailman.mit.edu/mailman/listinfo/piclist > > > > > -- > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > View/change your membership options at > > http://mailman.mit.edu/mailman/listinfo/piclist > > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .