BJT VBE auto adjust?

low voltage (1Vpeak) sine wave into a digital signal

to 5V from the collector. The signal is 1MHz, so I have added a baker clam p schotkky to avoid the BJT storage time

ase to keep it biased just below the point where the BJT knee kicks in (600 mV)

erature, 2mV/K

ording to the actual VBE knee (maybe check the digital side, if no signal, then I need to shift the bias up, and if it is clamped to GND, I need to sh ift the bias down)

would be the easy solution)

few

it works

e

et it to work

rying to pick it up at the other end with a sort of a AM modulation scheme. I have a cap on the output of the last BJT emitter, with a pull-up, so tha t I have a hold function when the NPN is turned on a regular intervals

ble. In HW it would also require a mixer and oscillator

y cycles to respond. A lock in could also work, but again takes additional complexity

I thought a simple FM detector was a filter followed by an AM detector. Th e filter passes the carrier through with different amplitude based on frequ ency turning it into AM modulation. I think the signal needs to be clipped to constant amplitude before the filter for best results. So a simple RC filter can be added to your detector and it's an FM receiver!

Can you easily frequency modulate your 1 MHz carrier?

--

  Rick C. 

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low voltage (1Vpeak) sine wave into a digital signal

to 5V from the collector. The signal is 1MHz, so I have added a baker clam p schotkky to avoid the BJT storage time

ase to keep it biased just below the point where the BJT knee kicks in (600 mV)

erature, 2mV/K

ording to the actual VBE knee (maybe check the digital side, if no signal, then I need to shift the bias up, and if it is clamped to GND, I need to sh ift the bias down)

would be the easy solution)

few

it works

e

et it to work

rying to pick it up at the other end with a sort of a AM modulation scheme. I have a cap on the output of the last BJT emitter, with a pull-up, so tha t I have a hold function when the NPN is turned on a regular intervals

ble. In HW it would also require a mixer and oscillator

y cycles to respond. A lock in could also work, but again takes additional complexity

what's the baudrate?

a low voltage (1Vpeak) sine wave into a digital signal

or to 5V from the collector. The signal is 1MHz, so I have added a baker cl amp schotkky to avoid the BJT storage time

base to keep it biased just below the point where the BJT knee kicks in (6

00mV)

mperature, 2mV/K

ccording to the actual VBE knee (maybe check the digital side, if no signal , then I need to shift the bias up, and if it is clamped to GND, I need to shift the bias down)

h would be the easy solution)

a few

ng

f it works

the

get it to work

trying to pick it up at the other end with a sort of a AM modulation schem e. I have a cap on the output of the last BJT emitter, with a pull-up, so t hat I have a hold function when the NPN is turned on a regular intervals

sable. In HW it would also require a mixer and oscillator

any cycles to respond. A lock in could also work, but again takes additiona l complexity

The filter passes the carrier through with different amplitude based on fre quency turning it into AM modulation. I think the signal needs to be clipp ed to constant amplitude before the filter for best results. So a simple R C filter can be added to your detector and it's an FM receiver!

The carrier is about 10MHz, and yes, cost is no concern on the generator si de

On Sunday, April 19, 2020 at 3:21:56 AM UTC+2, Lasse Langwadt Christensen w rote:

a low voltage (1Vpeak) sine wave into a digital signal

or to 5V from the collector. The signal is 1MHz, so I have added a baker cl amp schotkky to avoid the BJT storage time

base to keep it biased just below the point where the BJT knee kicks in (6

00mV)

mperature, 2mV/K

ccording to the actual VBE knee (maybe check the digital side, if no signal , then I need to shift the bias up, and if it is clamped to GND, I need to shift the bias down)

h would be the easy solution)

a few

ng

f it works

the

get it to work

trying to pick it up at the other end with a sort of a AM modulation schem e. I have a cap on the output of the last BJT emitter, with a pull-up, so t hat I have a hold function when the NPN is turned on a regular intervals

sable. In HW it would also require a mixer and oscillator

any cycles to respond. A lock in could also work, but again takes additiona l complexity

1Mbit/s

1Mbit modulation OOK on a 10MHz carrier is only a 10:1 ratio which seems pretty tough - can the data rate be lower?

piglet

On 19/04/2020 9:07 am, Klaus Kragelund wrote:

Hmm? OK here are two first pass attempts. The first uses a LC tank of moderate Q to raise the 100mV signal to more easily detectable level...

Version 4 SHEET 1 880 680 WIRE 720 -128 512 -128 WIRE 0 -112 -224 -112 WIRE -224 -96 -224 -112 WIRE 512 -96 512 -128 WIRE -224 0 -224 -16 WIRE -32 0 -224 0 WIRE 512 0 512 -16 WIRE 640 0 512 0 WIRE 80 16 -224 16 WIRE 512 16 512 0 WIRE 80 48 80 16 WIRE 720 48 720 -128 WIRE -32 64 -32 0 WIRE 32 64 -32 64 WIRE 400 64 320 64 WIRE 448 64 400 64 WIRE 320 80 320 64 WIRE 400 96 400 64 WIRE 0 112 0 -112 WIRE 32 112 0 112 WIRE 640 112 640 0 WIRE 80 160 80 128 WIRE 192 160 80 160 WIRE 320 160 320 144 WIRE 320 160 272 160 WIRE 80 176 80 160 WIRE 320 176 320 160 WIRE 0 192 0 112 WIRE 32 192 0 192 WIRE -224 208 -224 16 WIRE -32 240 -32 64 WIRE 32 240 -32 240 WIRE 320 272 320 240 WIRE 400 272 400 176 WIRE 512 272 512 112 WIRE 640 272 640 176 WIRE 720 272 720 128 WIRE 80 304 80 256 WIRE -224 336 -224 288 FLAG 80 304 0 FLAG -224 336 0 FLAG 640 272 0 FLAG 720 272 0 FLAG 320 272 0 FLAG 400 272 0 FLAG 512 272 0 FLAG 640 0 RXD SYMBOL voltage -224 -112 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value PULSE(1 -1 0 1n 1n 1u 2u) SYMBOL voltage -224 192 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V2 SYMATTR Value SINE(0 0.1 10meg) SYMBOL sw 80 32 R0 SYMATTR InstName S1 SYMATTR Value CSW SYMBOL sw 80 160 R0 SYMATTR InstName S2 SYMATTR Value CSW SYMBOL voltage 720 32 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V3 SYMATTR Value 3.3 SYMBOL res 496 -112 R0 SYMATTR InstName R1 SYMATTR Value 22k SYMBOL npn 448 16 R0 SYMATTR InstName Q1 SYMATTR Value 2N3904 SYMBOL cap 656 176 R180 WINDOW 0 24 56 Left 2 WINDOW 3 24 8 Left 2 SYMATTR InstName C3 SYMATTR Value 22p SYMBOL ind 384 80 R0 SYMATTR InstName L1

SYMATTR SpiceLine Rser=0.5 SYMBOL cap 304 80 R0 SYMATTR InstName C2 SYMATTR Value 47p SYMBOL cap 304 176 R0 SYMATTR InstName C1 SYMATTR Value 470p SYMBOL res 176 176 R270 WINDOW 0 32 56 VTop 2 WINDOW 3 0 56 VBottom 2 SYMATTR InstName Rsource SYMATTR Value 50 TEXT -112 352 Left 2 !.model CSW SW(Ron=1m Roff=1G Vt=0) TEXT -224 392 Left 2 !.tran 10u TEXT 24 392 Left 2 ;10MHz OOK at 1Mbaud TEXT 368 392 Left 2 ;Tuned Klaus Det SED - EPW Apr 2020

.... and this second version uses a second transistor amplifier if you can spare the extra parts count and standby current consumption ...

Version 4 SHEET 1 1124 680 WIRE 48 -112 -176 -112 WIRE 736 -112 512 -112 WIRE 896 -112 736 -112 WIRE -176 -96 -176 -112 WIRE 512 -80 512 -112 WIRE 736 -80 736 -112 WIRE -176 0 -176 -16 WIRE 0 0 -176 0 WIRE 16 0 0 0 WIRE 128 16 -176 16 WIRE 416 32 400 32 WIRE 512 32 512 0 WIRE 512 32 496 32 WIRE 128 48 128 16 WIRE 16 64 16 0 WIRE 80 64 16 64 WIRE 512 64 512 32 WIRE 592 64 512 64 WIRE 736 64 736 0 WIRE 848 64 736 64 WIRE 848 80 848 64 WIRE 48 112 48 -112 WIRE 80 112 48 112 WIRE 512 112 512 64 WIRE 512 112 496 112 WIRE 736 112 736 64 WIRE 896 144 896 -112 WIRE 128 160 128 128 WIRE 240 160 128 160 WIRE 336 160 320 160 WIRE 400 160 400 32 WIRE 400 160 384 160 WIRE 432 160 400 160 WIRE 592 160 592 128 WIRE 656 160 592 160 WIRE 672 160 656 160 WIRE 128 176 128 160 WIRE 48 192 48 112 WIRE 80 192 48 192 WIRE 656 192 656 160 WIRE -176 208 -176 16 WIRE 592 208 592 160 WIRE 16 240 16 64 WIRE 80 240 16 240 WIRE 128 304 128 256 WIRE 496 304 496 208 WIRE 592 304 592 272 WIRE 656 304 656 272 WIRE 736 304 736 208 WIRE 848 304 848 144 WIRE 896 304 896 224 WIRE -176 336 -176 288 FLAG 128 304 0 FLAG -176 336 0 FLAG 896 304 0 FLAG 496 304 0 FLAG 736 304 0 FLAG 848 304 0 FLAG 848 64 RXD FLAG 0 0 RXD FLAG 592 304 0 FLAG 656 304 0 SYMBOL voltage -176 -112 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value PULSE(1 -1 0 1n 1n 1u 2u) SYMBOL voltage -176 192 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V2 SYMATTR Value SINE(0 0.1 10meg) SYMBOL sw 128 32 R0 SYMATTR InstName S1 SYMATTR Value CSW SYMBOL sw 128 160 R0 SYMATTR InstName S2 SYMATTR Value CSW SYMBOL voltage 896 128 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V3 SYMATTR Value 3.3 SYMBOL res 720 -96 R0 SYMATTR InstName R4 SYMATTR Value 10k SYMBOL res 512 16 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R1 SYMATTR Value 220k SYMBOL npn 672 112 R0 SYMATTR InstName Q2 SYMATTR Value 2N3904 SYMBOL cap 400 144 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C1 SYMATTR Value 100p SYMBOL cap 864 144 R180 WINDOW 0 24 56 Left 2 WINDOW 3 24 8 Left 2 SYMATTR InstName C3 SYMATTR Value 22p SYMBOL res 336 144 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName Rsource SYMATTR Value 100 SYMBOL res 496 -96 R0 SYMATTR InstName R2 SYMATTR Value 2.2k SYMBOL npn 432 112 R0 SYMATTR InstName Q1 SYMATTR Value 2N3904 SYMBOL cap 576 64 R0 SYMATTR InstName C2 SYMATTR Value 100p SYMBOL diode 608 272 R180 WINDOW 0 24 64 Left 2 WINDOW 3 24 0 Left 2 SYMATTR InstName D1 SYMATTR Value 1N914 SYMBOL res 640 176 R0 SYMATTR InstName R3 SYMATTR Value 22k TEXT -96 352 Left 2 !.model CSW SW(Ron=1m Roff=1G Vt=0) TEXT -192 408 Left 2 !.tran 10u TEXT 504 408 Left 2 ;2Q Klaus Det SED - EPW Apr 2020 TEXT 88 408 Left 2 ;10MHz OOK at 1M baud

piglet

Are you running a radio connection or cable?

On cable, I'd recommend trying to use a Manchester coding scheme and send the baseband as is.

--

-TV

Very nice indeed. That last one has what I need, and not expensive at all, so I will go deeper into that one. Thanks a lot :-)

a low voltage (1Vpeak) sine wave into a digital signal

or to 5V from the collector. The signal is 1MHz, so I have added a baker cl amp schotkky to avoid the BJT storage time

base to keep it biased just below the point where the BJT knee kicks in (6

00mV)

mperature, 2mV/K

ccording to the actual VBE knee (maybe check the digital side, if no signal , then I need to shift the bias up, and if it is clamped to GND, I need to shift the bias down)

h would be the easy solution)

a few

ng

f it works

the

get it to work

trying to pick it up at the other end with a sort of a AM modulation schem e. I have a cap on the output of the last BJT emitter, with a pull-up, so t hat I have a hold function when the NPN is turned on a regular intervals

easable. In HW it would also require a mixer and oscillator

many cycles to respond. A lock in could also work, but again takes additio nal complexity

I am on a radio connection, so not really possible to operate directly at t he baseband

Cheers

Klaus