Simple front end circuit recommendation?

I’m looking for the simplest circuit that would achieve the following please.
SUPPLY:
18V DC, possibly from two PP3s.

INPUT:
A high or low going DC voltage, with max of 5-15V, with varying input impedance, say 1k < 1M. Two input ports, with only one in use of course. (I’m assuming it’s impossible or complex
to achieve with only one input for the two polarities.)

TWO OUTPUTS:
One low going, the other high going, both at lowish impedance, day 470R .

All suggestions would be much appreciated please.

Terry, UK

 

[Lasse Langwadt Christense]

mandag den 30. marts 2020 kl. 19.18.59 UTC+2 skrev terry...@gmail.com:

I’m looking for the simplest circuit that would achieve the following please.
SUPPLY:
18V DC, possibly from two PP3s.

INPUT:
A high or low going DC voltage, with max of 5-15V, with varying input impedance, say 1k < 1M. Two input ports, with only one in use of course. (I’m assuming it’s impossible or complex
to achieve with only one input for the two polarities.)

TWO OUTPUTS:
One low going, the other high going, both at lowish impedance, day 470R .

All suggestions would be much appreciated please.

Terry, UK

http://xyproblem.info/

 

[Rick C]

On Monday, March 30, 2020 at 1:46:45 PM UTC-4, George Herold wrote:

On Monday, March 30, 2020 at 1:18:59 PM UTC-4, terry...@gmail.com wrote:
I’m looking for the simplest circuit that would achieve the following please.
SUPPLY:
18V DC, possibly from two PP3s.

INPUT:
A high or low going DC voltage, with max of 5-15V, with varying input impedance, say 1k < 1M. Two input ports, with only one in use of course. (I’m assuming it’s impossible or complex
to achieve with only one input for the two polarities.)

TWO OUTPUTS:
One low going, the other high going, both at lowish impedance, day 470R .

All suggestions would be much appreciated please.

Terry, UK

Terry, that's confusing.
Can you write an equation that relates the outputs to the input?

George h.

Or even a more clear English description. What is a "high or low going DC voltage"? Do you mean of either polarity?

Is the output intended to be both positive and negative? What voltage? The same as the input? Lower than the input?

If you are asking for a circuit that accepts low current inputs and higher current outputs at the same voltage without another power supply you ain't going to find it.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

 

[George Herold]

On Monday, March 30, 2020 at 1:18:59 PM UTC-4, terry...@gmail.com wrote:

I’m looking for the simplest circuit that would achieve the following please.
SUPPLY:
18V DC, possibly from two PP3s.

INPUT:
A high or low going DC voltage, with max of 5-15V, with varying input impedance, say 1k < 1M. Two input ports, with only one in use of course. (I’m assuming it’s impossible or complex
to achieve with only one input for the two polarities.)

TWO OUTPUTS:
One low going, the other high going, both at lowish impedance, day 470R .

All suggestions would be much appreciated please.

Terry, UK

Terry, that's confusing.
Can you write an equation that relates the outputs to the input?

George h.

 

[whit3rd]

On Monday, March 30, 2020 at 10:18:59 AM UTC-7, terry...@gmail.com wrote:
> I’m looking for the simplest circuit that would ...

A quad op amp, with two sections used as voltage followers, and two as inverters
should suffice. You'd need to switch one or the other of the follower outputs
to the cascaded inverters.

Something like TL064 would be relatively easy on the battery power.

For preference, I'd want to do some attenuation (even if the inputs tolerate
5-15V, making the outputs drive that full range can be problematic).
So, maybe the first inverter can be a gain-of-0.5. An array of 5 matched
resistors will be the passive component complement.

If you intend +15V to -15V input range, the power supply will have to be
+/-15V, and not +/- 9V.

 

Thanks, I’ll try that 064 idea tomorrow if I have any at hand. If not maybe I can adapt a couple of 741s.

Terry

 

George,

Not confident I can condense it to an equation, but I’ll have another stab at describing what is essentially just a simple DC voltage follower plus inverter. One input A and two outputs B and C. Typical input sources might be from a simple micro switch, PIR sensor, IR Detector, etc. In broad terms, pulses. Either high or low going. Typically fast enough to make a Schmitt unnecessary. Capable of say at least 30mA output.

Supply would be either from my bench unit or an internal battery (or two for 18V). Obviously Vcc would determine the allowable input level and the maximum output level.

I envisage a small case with an input phono on one side and two output photos on the other, with Vcc to a fourth.

I already have various devices, typically made a few decades ago in 2oz tobacco tins, that could achieve the same purpose, but they’re mostly more versatile/complex. This project is for a compact ultra simple, no-brainer tool.

Terry

 

[George Herold]

On Tuesday, March 31, 2020 at 8:50:22 AM UTC-4, terry...@gmail.com wrote:

George,

Not confident I can condense it to an equation, but I’ll have another stab at describing what is essentially just a simple DC voltage follower plus inverter. One input A and two outputs B and C. Typical input sources might be from a simple micro switch, PIR sensor, IR Detector, etc. In broad terms, pulses. Either high or low going. Typically fast enough to make a Schmitt unnecessary. Capable of say at least 30mA output.

Supply would be either from my bench unit or an internal battery (or two for 18V). Obviously Vcc would determine the allowable input level and the maximum output level.

I envisage a small case with an input phono on one side and two output photos on the other, with Vcc to a fourth.

I already have various devices, typically made a few decades ago in 2oz tobacco tins, that could achieve the same purpose, but they’re mostly more versatile/complex. This project is for a compact ultra simple, no-brainer tool.

Terry

Are the outputs digital or analog voltages?
If analog then some opamp as whit3rd said. 18V and 500 ohms
is 36mA so pick an opamp with enough current drive.

George H.

 

[Terry Pinnell]

George Herold <ggherold@gmail.com> wrote:

On Tuesday, March 31, 2020 at 8:50:22 AM UTC-4, terry...@gmail.com wrote:
George,

Not confident I can condense it to an equation, but I’ll have another stab at describing what is essentially just a simple DC voltage follower plus inverter. One input A and two outputs B and C. Typical input sources might be from a simple micro switch, PIR sensor, IR Detector, etc. In broad terms, pulses. Either high or low going. Typically fast enough to make a Schmitt unnecessary. Capable of say at least 30mA output.

Supply would be either from my bench unit or an internal battery (or two for 18V). Obviously Vcc would determine the allowable input level and the maximum output level.

I envisage a small case with an input phono on one side and two output photos on the other, with Vcc to a fourth.

I already have various devices, typically made a few decades ago in 2oz tobacco tins, that could achieve the same purpose, but they’re mostly more versatile/complex. This project is for a compact ultra simple, no-brainer tool.

Terry

Are the outputs digital or analog voltages?
If analog then some opamp as whit3rd said. 18V and 500 ohms
is 36mA so pick an opamp with enough current drive.

George H.

They follow the inputs, which are analog.

 

[Rick C]

On Tuesday, March 31, 2020 at 9:54:28 AM UTC-4, George Herold wrote:

On Tuesday, March 31, 2020 at 8:50:22 AM UTC-4, terry...@gmail.com wrote:
George,

Not confident I can condense it to an equation, but I’ll have another stab at describing what is essentially just a simple DC voltage follower plus inverter. One input A and two outputs B and C. Typical input sources might be from a simple micro switch, PIR sensor, IR Detector, etc. In broad terms, pulses. Either high or low going. Typically fast enough to make a Schmitt unnecessary. Capable of say at least 30mA output.

Supply would be either from my bench unit or an internal battery (or two for 18V). Obviously Vcc would determine the allowable input level and the maximum output level.

I envisage a small case with an input phono on one side and two output photos on the other, with Vcc to a fourth.

I already have various devices, typically made a few decades ago in 2oz tobacco tins, that could achieve the same purpose, but they’re mostly more versatile/complex. This project is for a compact ultra simple, no-brainer tool.

Terry

Are the outputs digital or analog voltages?
If analog then some opamp as whit3rd said. 18V and 500 ohms
is 36mA so pick an opamp with enough current drive.

LM8272 is a good choice able to drive well above 36 mA. It also drives a capacitive load without stability issues which may be important if you are driving long wires or coax. It's a dual so you only need one. However, it only comes in a surface mount package, MSOP8. The similar LM7322 comes in an 8 pin SOIC which is much larger even if not a DIP.

--

Rick C.

+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209

 

[George Herold]

On Tuesday, March 31, 2020 at 12:58:39 PM UTC-4, Terry Pinnell wrote:

George Herold <ggherold@gmail.com> wrote:

On Tuesday, March 31, 2020 at 8:50:22 AM UTC-4, terry...@gmail.com wrote:
George,

Not confident I can condense it to an equation, but I’ll have another stab at describing what is essentially just a simple DC voltage follower plus inverter. One input A and two outputs B and C. Typical input sources might be from a simple micro switch, PIR sensor, IR Detector, etc. In broad terms, pulses. Either high or low going. Typically fast enough to make a Schmitt unnecessary. Capable of say at least 30mA output.

Supply would be either from my bench unit or an internal battery (or two for 18V). Obviously Vcc would determine the allowable input level and the maximum output level.

I envisage a small case with an input phono on one side and two output photos on the other, with Vcc to a fourth.

I already have various devices, typically made a few decades ago in 2oz tobacco tins, that could achieve the same purpose, but they’re mostly more versatile/complex. This project is for a compact ultra simple, no-brainer tool.

Terry

Are the outputs digital or analog voltages?
If analog then some opamp as whit3rd said. 18V and 500 ohms
is 36mA so pick an opamp with enough current drive.

George H.

They follow the inputs, which are analog.

Oh but single supply.
So V_in(t) is always positive and
VA_out = V_in
and
VB_out = 15V - V_in
(you could have some offset other than 15V)
Is that right?

George H.

 

[Terry Pinnell]

George Herold <ggherold@gmail.com> wrote:

On Tuesday, March 31, 2020 at 12:58:39 PM UTC-4, Terry Pinnell wrote:
George Herold <ggherold@gmail.com> wrote:

On Tuesday, March 31, 2020 at 8:50:22 AM UTC-4, terry...@gmail.com wrote:
George,

Not confident I can condense it to an equation, but I’ll have another stab at describing what is essentially just a simple DC voltage follower plus inverter. One input A and two outputs B and C. Typical input sources might be from a simple micro switch, PIR sensor, IR Detector, etc. In broad terms, pulses. Either high or low going. Typically fast enough to make a Schmitt unnecessary. Capable of say at least 30mA output.

Supply would be either from my bench unit or an internal battery (or two for 18V). Obviously Vcc would determine the allowable input level and the maximum output level.

I envisage a small case with an input phono on one side and two output photos on the other, with Vcc to a fourth.

I already have various devices, typically made a few decades ago in 2oz tobacco tins, that could achieve the same purpose, but they’re mostly more versatile/complex. This project is for a compact ultra simple, no-brainer tool.

Terry

Are the outputs digital or analog voltages?
If analog then some opamp as whit3rd said. 18V and 500 ohms
is 36mA so pick an opamp with enough current drive.

George H.

They follow the inputs, which are analog.

Oh but single supply.
So V_in(t) is always positive and
VA_out = V_in
and
VB_out = 15V - V_in
(you could have some offset other than 15V)
Is that right?

George H.

Yes, that's correct.

I've breadboarded a simple 741 voltage follower with a 0-18V supply,
split with two 470R resistors, followed by an NPN buffer with 270R in
its emitter. Output is about 0.4V below input and follows it from about
2V to 16V (acceptable for my purposes), delivering about 80mA.

I now need to add an equally simple inverter circuit.

Will probably not incorporate internal batteries after all. For
relatively infrequent use away from my workbench I'll just rig up a
couple of series PP3s to a phono socket.

P.S. Ruled out 064 etc as I try to avoid the inconvenience of dual
polarity supplies.

Terry

 

[George Herold]

On Thursday, April 2, 2020 at 9:28:20 AM UTC-4, Terry Pinnell wrote:

George Herold <ggherold@gmail.com> wrote:

On Tuesday, March 31, 2020 at 12:58:39 PM UTC-4, Terry Pinnell wrote:
George Herold <ggherold@gmail.com> wrote:

On Tuesday, March 31, 2020 at 8:50:22 AM UTC-4, terry...@gmail.com wrote:
George,

Not confident I can condense it to an equation, but I’ll have another stab at describing what is essentially just a simple DC voltage follower plus inverter. One input A and two outputs B and C. Typical input sources might be from a simple micro switch, PIR sensor, IR Detector, etc. In broad terms, pulses. Either high or low going. Typically fast enough to make a Schmitt unnecessary. Capable of say at least 30mA output.

Supply would be either from my bench unit or an internal battery (or two for 18V). Obviously Vcc would determine the allowable input level and the maximum output level.

I envisage a small case with an input phono on one side and two output photos on the other, with Vcc to a fourth.

I already have various devices, typically made a few decades ago in 2oz tobacco tins, that could achieve the same purpose, but they’re mostly more versatile/complex. This project is for a compact ultra simple, no-brainer tool.

Terry

Are the outputs digital or analog voltages?
If analog then some opamp as whit3rd said. 18V and 500 ohms
is 36mA so pick an opamp with enough current drive.

George H.

They follow the inputs, which are analog.

Oh but single supply.
So V_in(t) is always positive and
VA_out = V_in
and
VB_out = 15V - V_in
(you could have some offset other than 15V)
Is that right?

George H.

Yes, that's correct.

I've breadboarded a simple 741 voltage follower with a 0-18V supply,
split with two 470R resistors, followed by an NPN buffer with 270R in
its emitter. Output is about 0.4V below input and follows it from about
2V to 16V (acceptable for my purposes), delivering about 80mA.

I now need to add an equally simple inverter circuit.

I think that's easy.
Single supply say +18V and ground.
V-in goes to an inverting input through R (and R feedback..
an inverting amp)
now make a 15V reference and apply that to the non-inverting input.
(I think that works...)
(I'm sure someone will correct me if it doesn't)
George H.

Will probably not incorporate internal batteries after all. For
relatively infrequent use away from my workbench I'll just rig up a
couple of series PP3s to a phono socket.

P.S. Ruled out 064 etc as I try to avoid the inconvenience of dual
polarity supplies.

Terry

 

[Rick C]

On Thursday, April 2, 2020 at 9:28:20 AM UTC-4, Terry Pinnell wrote:

George Herold <ggherold@gmail.com> wrote:

On Tuesday, March 31, 2020 at 12:58:39 PM UTC-4, Terry Pinnell wrote:
George Herold <ggherold@gmail.com> wrote:

On Tuesday, March 31, 2020 at 8:50:22 AM UTC-4, terry...@gmail.com wrote:
George,

Not confident I can condense it to an equation, but I’ll have another stab at describing what is essentially just a simple DC voltage follower plus inverter. One input A and two outputs B and C. Typical input sources might be from a simple micro switch, PIR sensor, IR Detector, etc. In broad terms, pulses. Either high or low going. Typically fast enough to make a Schmitt unnecessary. Capable of say at least 30mA output.

Supply would be either from my bench unit or an internal battery (or two for 18V). Obviously Vcc would determine the allowable input level and the maximum output level.

I envisage a small case with an input phono on one side and two output photos on the other, with Vcc to a fourth.

I already have various devices, typically made a few decades ago in 2oz tobacco tins, that could achieve the same purpose, but they’re mostly more versatile/complex. This project is for a compact ultra simple, no-brainer tool.

Terry

Are the outputs digital or analog voltages?
If analog then some opamp as whit3rd said. 18V and 500 ohms
is 36mA so pick an opamp with enough current drive.

George H.

They follow the inputs, which are analog.

Oh but single supply.
So V_in(t) is always positive and
VA_out = V_in
and
VB_out = 15V - V_in
(you could have some offset other than 15V)
Is that right?

George H.

Yes, that's correct.

I've breadboarded a simple 741 voltage follower with a 0-18V supply,
split with two 470R resistors, followed by an NPN buffer with 270R in
its emitter. Output is about 0.4V below input and follows it from about
2V to 16V (acceptable for my purposes), delivering about 80mA.

I now need to add an equally simple inverter circuit.

Will probably not incorporate internal batteries after all. For
relatively infrequent use away from my workbench I'll just rig up a
couple of series PP3s to a phono socket.

P.S. Ruled out 064 etc as I try to avoid the inconvenience of dual
polarity supplies.

Terry

If you are using two batteries, you already have a split supply. If you don't split the supply, how will you support positive and negative outputs?

--

Rick C.

-- Get 1,000 miles of free Supercharging
-- Tesla referral code - https://ts.la/richard11209

 

[Rick C]

On Thursday, April 2, 2020 at 10:12:14 AM UTC-4, George Herold wrote:

On Thursday, April 2, 2020 at 9:28:20 AM UTC-4, Terry Pinnell wrote:
George Herold <ggherold@gmail.com> wrote:

On Tuesday, March 31, 2020 at 12:58:39 PM UTC-4, Terry Pinnell wrote:
George Herold <ggherold@gmail.com> wrote:

On Tuesday, March 31, 2020 at 8:50:22 AM UTC-4, terry...@gmail.com wrote:
George,

Not confident I can condense it to an equation, but I’ll have another stab at describing what is essentially just a simple DC voltage follower plus inverter. One input A and two outputs B and C. Typical input sources might be from a simple micro switch, PIR sensor, IR Detector, etc.. In broad terms, pulses. Either high or low going. Typically fast enough to make a Schmitt unnecessary. Capable of say at least 30mA output.

Supply would be either from my bench unit or an internal battery (or two for 18V). Obviously Vcc would determine the allowable input level and the maximum output level.

I envisage a small case with an input phono on one side and two output photos on the other, with Vcc to a fourth.

I already have various devices, typically made a few decades ago in 2oz tobacco tins, that could achieve the same purpose, but they’re mostly more versatile/complex. This project is for a compact ultra simple, no-brainer tool.

Terry

Are the outputs digital or analog voltages?
If analog then some opamp as whit3rd said. 18V and 500 ohms
is 36mA so pick an opamp with enough current drive.

George H.

They follow the inputs, which are analog.

Oh but single supply.
So V_in(t) is always positive and
VA_out = V_in
and
VB_out = 15V - V_in
(you could have some offset other than 15V)
Is that right?

George H.

Yes, that's correct.

I've breadboarded a simple 741 voltage follower with a 0-18V supply,
split with two 470R resistors, followed by an NPN buffer with 270R in
its emitter. Output is about 0.4V below input and follows it from about
2V to 16V (acceptable for my purposes), delivering about 80mA.

I now need to add an equally simple inverter circuit.
I think that's easy.
Single supply say +18V and ground.
V-in goes to an inverting input through R (and R feedback..
an inverting amp)
now make a 15V reference and apply that to the non-inverting input.
(I think that works...)
(I'm sure someone will correct me if it doesn't)
George H.

Works to do what? Doesn't he want complementary outputs?

This is starting to remind me of the customers in the YouTube video "The Expert". "Three red lines made with green ink."

--

Rick C.

-+ Get 1,000 miles of free Supercharging
-+ Tesla referral code - https://ts.la/richard11209

 

On Thursday, April 2, 2020 at 3:12:14 PM UTC+1, George Herold wrote:

On Thursday, April 2, 2020 at 9:28:20 AM UTC-4, Terry Pinnell wrote:
George Herold <ggherold@gmail.com> wrote:

On Tuesday, March 31, 2020 at 12:58:39 PM UTC-4, Terry Pinnell wrote:
George Herold <ggherold@gmail.com> wrote:

On Tuesday, March 31, 2020 at 8:50:22 AM UTC-4, terry...@gmail.com wrote:
George,

Not confident I can condense it to an equation, but I’ll have another stab at describing what is essentially just a simple DC voltage follower plus inverter. One input A and two outputs B and C. Typical input sources might be from a simple micro switch, PIR sensor, IR Detector, etc.. In broad terms, pulses. Either high or low going. Typically fast enough to make a Schmitt unnecessary. Capable of say at least 30mA output.

Supply would be either from my bench unit or an internal battery (or two for 18V). Obviously Vcc would determine the allowable input level and the maximum output level.

I envisage a small case with an input phono on one side and two output photos on the other, with Vcc to a fourth.

I already have various devices, typically made a few decades ago in 2oz tobacco tins, that could achieve the same purpose, but they’re mostly more versatile/complex. This project is for a compact ultra simple, no-brainer tool.

Terry

Are the outputs digital or analog voltages?
If analog then some opamp as whit3rd said. 18V and 500 ohms
is 36mA so pick an opamp with enough current drive.

George H.

They follow the inputs, which are analog.

Oh but single supply.
So V_in(t) is always positive and
VA_out = V_in
and
VB_out = 15V - V_in
(you could have some offset other than 15V)
Is that right?

George H.

Yes, that's correct.

I've breadboarded a simple 741 voltage follower with a 0-18V supply,
split with two 470R resistors, followed by an NPN buffer with 270R in
its emitter. Output is about 0.4V below input and follows it from about
2V to 16V (acceptable for my purposes), delivering about 80mA.

I now need to add an equally simple inverter circuit.
I think that's easy.
Single supply say +18V and ground.
V-in goes to an inverting input through R (and R feedback..
an inverting amp)
now make a 15V reference and apply that to the non-inverting input.
(I think that works...)
(I'm sure someone will correct me if it doesn't)
George H.

Will probably not incorporate internal batteries after all. For
relatively infrequent use away from my workbench I'll just rig up a
couple of series PP3s to a phono socket.

P.S. Ruled out 064 etc as I try to avoid the inconvenience of dual
polarity supplies.

Terry

Thanks George, but the following seems to work OK:

https://www.dropbox.com/s/wyrgjgmxwtclk5f/VoltageFollower-1.jpg?raw=1

Happily after some experiment I was able to avoid an artificial slot supply..

The output follows input when above 2V up to about 16V. (Well, one BE voltage lower, which is acceptable for my purposes.)

Need to add the inverter circuit now.

Terry