Forums

Transistor Phase Inverter Values

Started by Unknown September 28, 2013
I have a complex low frequency signal from which I need to produce two
outputs of equal amplitude but inverted in phase. I would prefer not
to use a transformer due to size.

Here is the circuit I am considering.

http://www.4shared.com/photo/CDpvTMJW/43_1_Large_Signal_Amplifiers.html

This is low current, so I would just use a BC547 or the like.

Can anyone please tell me how to properly select the R values for a
voltage gain of around 2x?

The nominal frequency of the signal is about 30Hz. Will using large
vakue coupling caps compromise the intended performance in any way?

Mark Newman
On Sun, 29 Sep 2013 07:43:06 +1000, mnewman@keystone.com wrote:

> >I have a complex low frequency signal from which I need to produce two >outputs of equal amplitude but inverted in phase. I would prefer not >to use a transformer due to size. > >Here is the circuit I am considering. > >http://www.4shared.com/photo/CDpvTMJW/43_1_Large_Signal_Amplifiers.html > >This is low current, so I would just use a BC547 or the like. > >Can anyone please tell me how to properly select the R values for a >voltage gain of around 2x?
10K, 10K, 2K, 2K. The gains are inherently +1 and -1. You can consider that to be 2x if you measure diff_out/se_in.
> >The nominal frequency of the signal is about 30Hz. Will using large >vakue coupling caps compromise the intended performance in any way?
What's the intended performance? -- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
"John Larkin"
> >>Here is the circuit I am considering. >> >>http://www.4shared.com/photo/CDpvTMJW/43_1_Large_Signal_Amplifiers.html >> >>This is low current, so I would just use a BC547 or the like. >> >>Can anyone please tell me how to properly select the R values for a >>voltage gain of around 2x? > > 10K, 10K, 2K, 2K.
** You sure about that ? With those values the transistor is almost saturated and the available swing at each output is tiny. Assuming Vcc is 20V, set Vbase at 5.6V Makes R1 = 27k and R2 = 10k Re=Rc = 2k. ... Phil
This is a poorman's solution unless you are going into high impedances on the collector.  Two Op Amps or differential amps are generally preferred for matched inverted outputs.
"Anthony Stewart"

> This is a poorman's solution unless you are going into high impedances on > the collector.
** Really - why? And don't come out with the old furphy that the source impedances are different.
> Two Op Amps or differential amps are generally preferred for matched > inverted outputs.
** You clearly do not understand the one transistor PI circuit. ... Phil
On Sat, 28 Sep 2013 14:51:03 -0700, John Larkin
<jlarkin@highlandtechnology.com> wrote:


>>Here is the circuit I am considering. >> >>http://www.4shared.com/photo/CDpvTMJW/43_1_Large_Signal_Amplifiers.html >>
>What's the intended performance?
Sorry everyone, I should have mentioned Vcc is 6V. As for performance, the circuit is just driving two 100 Ohm resistive loads. Just a lttle experiment. Nothing critical. Given a 30Hz signal, what would be a good value forthe caps? Mark Newman
On Sun, 29 Sep 2013 14:15:07 +1000, "Phil Allison" <phil_a@tpg.com.au>
wrote:


>> 10K, 10K, 2K, 2K. >
>With those values the transistor is almost saturated and the available swing >at each output is tiny. > >Assuming Vcc is 20V, set Vbase at 5.6V > >Makes R1 = 27k and R2 = 10k > >Re=Rc = 2k. > > >... Phil >
Thanks Phil, but what would be the values if Vcc is 6 volts? I should have mentioned that. Mark Newman
On 29.9.13 10:56 , mnewman@keystone.com wrote:
> On Sat, 28 Sep 2013 14:51:03 -0700, John Larkin > <jlarkin@highlandtechnology.com> wrote: > > >>> Here is the circuit I am considering. >>> >>> http://www.4shared.com/photo/CDpvTMJW/43_1_Large_Signal_Amplifiers.html >>> > >> What's the intended performance? > > Sorry everyone, I should have mentioned Vcc is 6V. As for performance, > the circuit is just driving two 100 Ohm resistive loads. > > Just a lttle experiment. Nothing critical. > > Given a 30Hz signal, what would be a good value forthe caps? > > Mark Newman
A VOR receiver? The cap value depends much on the load impedance and required phase accuracy. I'd use operational amplifiers. -- Tauno Voipio
On 2013-09-29, mnewman@keystone.com <mnewman@keystone.com> wrote:
> On Sat, 28 Sep 2013 14:51:03 -0700, John Larkin ><jlarkin@highlandtechnology.com> wrote: > > >>>Here is the circuit I am considering. >>> >>>http://www.4shared.com/photo/CDpvTMJW/43_1_Large_Signal_Amplifiers.html >>> > >>What's the intended performance? > > Sorry everyone, I should have mentioned Vcc is 6V. As for performance, > the circuit is just driving two 100 Ohm resistive loads.
what's at the other end of the loads? can you just put the two loads in series or in parallel with one of them backwards? -- &#9858;&#9859; 100% natural --- news://freenews.netfront.net/ - complaints: news@netfront.net ---
<mnewman@keystone.com>
> > >>>Here is the circuit I am considering. >>> >>>http://www.4shared.com/photo/CDpvTMJW/43_1_Large_Signal_Amplifiers.html >>> > >>What's the intended performance? > > Sorry everyone, I should have mentioned Vcc is 6V. As for performance, > the circuit is just driving two 100 Ohm resistive loads. > > Just a lttle experiment. Nothing critical. > > Given a 30Hz signal, what would be a good value forthe caps? > > Mark Newman >
** Time to come inside - Mark. Alfred E. wants to speak to you. .... Phil