Skip to main content
added 260 characters in body
Source Link
D.A.S.
  • 148k
  • 3
  • 56
  • 190

If you know the CTR and that is like hFE except due to coupling loss may be CTR=25% worst case, a first glance tells me looking and V/R ratios it not reliable. 5/3.3V * (1k+1k)/4.7k needs CTR>100%.

Also you need voltage gain, so with the lousy current gain with load on collector using 10Rin to get voltage gain to compensate for low CTR using common emitter, NOT emitter follower.

So invert switching on output after this if needed with logic.

Look at it as a simple NPN switch with Rb =1K and Rc>= 10k. But instead of Ic/Ib=10 , consider Ic/Ib= 0.1 then it will work.

There is no need to to use rated LED current but for long term you must use at least 10% max current. (Prevent aging)

After reading spec CTR Min is 50%30% Vce(sat) @ If=1mA

Use common emitter with collector R= 10km for voltage gain.

As long as Ic/Ib >30% with loss of gain when saturated. It should work.

Spec is If=1mA CTR saturated =30% min. Ib=5V-Vf=1.2V/200 = 3.8V/2K=1.9 mA. X 30% into 3.3V = Rc= 5.7k Min

If you know the CTR and that is like hFE except due to coupling loss may be CTR=25% worst case, a first glance tells me looking and V/R ratios it not reliable. 5/3.3V * (1k+1k)/4.7k needs CTR>100%.

Also you need voltage gain, so with the lousy current gain with load on collector using 10Rin to get voltage gain to compensate for low CTR using common emitter, NOT emitter follower.

So invert switching on output after this if needed with logic.

Look at it as a simple NPN switch with Rb =1K and Rc>= 10k. But instead of Ic/Ib=10 , consider Ic/Ib= 0.1 then it will work.

There is no need to to use rated LED current but for long term you must use at least 10% max current. (Prevent aging)

After reading spec CTR Min is 50%

If you know the CTR and that is like hFE except due to coupling loss may be CTR=25% worst case, a first glance tells me looking and V/R ratios it not reliable. 5/3.3V * (1k+1k)/4.7k needs CTR>100%.

Also you need voltage gain, so with the lousy current gain with load on collector using 10Rin to get voltage gain to compensate for low CTR using common emitter, NOT emitter follower.

So invert switching on output after this if needed with logic.

Look at it as a simple NPN switch with Rb =1K and Rc>= 10k. But instead of Ic/Ib=10 , consider Ic/Ib= 0.1 then it will work.

There is no need to to use rated LED current but for long term you must use at least 10% max current. (Prevent aging)

After reading spec CTR Min is 30% Vce(sat) @ If=1mA

Use common emitter with collector R= 10km for voltage gain.

As long as Ic/Ib >30% with loss of gain when saturated. It should work.

Spec is If=1mA CTR saturated =30% min. Ib=5V-Vf=1.2V/200 = 3.8V/2K=1.9 mA. X 30% into 3.3V = Rc= 5.7k Min

edited body; added 3 characters in body; added 35 characters in body
Source Link
D.A.S.
  • 148k
  • 3
  • 56
  • 190

If you know the CTR and that is like hFE except due to coupling loss may be CTR=25% worst case, a first glance tells me looking and V/R ratios it not reliable. 5/3.3V * (1k+1k)/34.3k7k needs CTR>100%.

Also you need voltage gain, so with the lousy current gain with load on collector using 10Rin to get voltage gain to compensate for low CTR using common emitter, NOT emitter follower.

So invert switching on output after this if needed with logic.

Look at it as a simple NPN switch with Rb =1K and Rc>= 10k. But instead of Ic/Ib=10 , consider Ic/Ib= 0.1 then it will work.

There is no need to to use rated LED current but for long term you must use at least 10% max current. (Prevent aging)

After reading spec CTR Min is 50%

If you know the CTR and that like hFE except due to coupling loss may be CTR=25% worst case, a first glance tells me looking and V/R ratios it not reliable. 5/3.3V * (1k+1k)/3.3k needs CTR>100%.

Also you need voltage gain, so with the lousy current gain with load on collector using 10Rin to get voltage gain to compensate for low CTR using common emitter, NOT emitter follower.

So invert switching on output after this if needed with logic.

Look at it as a simple NPN switch with Rb =1K and Rc>= 10k. But instead of Ic/Ib=10 , consider Ic/Ib= 0.1 then it will work.

There is no need to to use rated LED current but for long term you must use at least 10% max current. (Prevent aging)

If you know the CTR and that is like hFE except due to coupling loss may be CTR=25% worst case, a first glance tells me looking and V/R ratios it not reliable. 5/3.3V * (1k+1k)/4.7k needs CTR>100%.

Also you need voltage gain, so with the lousy current gain with load on collector using 10Rin to get voltage gain to compensate for low CTR using common emitter, NOT emitter follower.

So invert switching on output after this if needed with logic.

Look at it as a simple NPN switch with Rb =1K and Rc>= 10k. But instead of Ic/Ib=10 , consider Ic/Ib= 0.1 then it will work.

There is no need to to use rated LED current but for long term you must use at least 10% max current. (Prevent aging)

After reading spec CTR Min is 50%

Source Link
D.A.S.
  • 148k
  • 3
  • 56
  • 190

If you know the CTR and that like hFE except due to coupling loss may be CTR=25% worst case, a first glance tells me looking and V/R ratios it not reliable. 5/3.3V * (1k+1k)/3.3k needs CTR>100%.

Also you need voltage gain, so with the lousy current gain with load on collector using 10Rin to get voltage gain to compensate for low CTR using common emitter, NOT emitter follower.

So invert switching on output after this if needed with logic.

Look at it as a simple NPN switch with Rb =1K and Rc>= 10k. But instead of Ic/Ib=10 , consider Ic/Ib= 0.1 then it will work.

There is no need to to use rated LED current but for long term you must use at least 10% max current. (Prevent aging)