f*h
2 楼
nero 6英文版,xp pro中文版,烧cd的时候没有报错,但读的时候不认。烧的是一般的
照片文档之类的数据。请问大侠,这可能是什么地方的问题?谢谢!
照片文档之类的数据。请问大侠,这可能是什么地方的问题?谢谢!
x*9
3 楼
用现有的0V/0.5V DC输出 控制 110VAC, 1A的交流电路
要求当控制输出由0.5V变成0V时,切断交流电路起到保护的作用
要求当控制输出由0.5V变成0V时,切断交流电路起到保护的作用
d*s
9 楼
楼上的我是dallas
f*0
13 楼
0.5v trigger is tough to do, as it wouldn't be enough to turn on a bjt.
a few posibilities:
a) you can use some depletion mosfet which conducts at all voltage types.
b) you can use a comparator, preferrably single rail type. like lm311.
c) form a 0.2 - 0.5v supply, and apply it to the base of a npn bjt. type
emitter of your bjt to your control signal, and your relay to the collector.
when the control signal is at 0.5v, the be junction doesn't get enough
signal to turn on the bjt so the relay sta
a few posibilities:
a) you can use some depletion mosfet which conducts at all voltage types.
b) you can use a comparator, preferrably single rail type. like lm311.
c) form a 0.2 - 0.5v supply, and apply it to the base of a npn bjt. type
emitter of your bjt to your control signal, and your relay to the collector.
when the control signal is at 0.5v, the be junction doesn't get enough
signal to turn on the bjt so the relay sta
f*0
15 楼
the problem with using a depletion type mosfet is that most of those devices
don't have a clear turn on threshold. they gradually turn on and this can
be a death knoll in a switching application like yours.
don't have a clear turn on threshold. they gradually turn on and this can
be a death knoll in a switching application like yours.
f*0
17 楼
another approach may be to use some low power 555. the 2 triggers go off at
1/3 and 2/3 of Vcc so if you can get some 555 that runs on 1v Vcc you would
have a solution.
1/3 and 2/3 of Vcc so if you can get some 555 that runs on 1v Vcc you would
have a solution.
f*0
19 楼
another solution is to use germanium transistors. those suckers turn on at 0
.2v vs. 0.6v for a silicon transistor.
that is an almost perfect solution for you: germanium transistors don't turn
completely on. but you can use it to drivea mosfet / silicon tansistor.
the old 3ax31 from China probably go for cents now, and nte has a lot of
germanium transistors.
.2v vs. 0.6v for a silicon transistor.
that is an almost perfect solution for you: germanium transistors don't turn
completely on. but you can use it to drivea mosfet / silicon tansistor.
the old 3ax31 from China probably go for cents now, and nte has a lot of
germanium transistors.
g*u
21 楼
check for some logic gate chips, some should have amplifier built inside.
b*e
22 楼
老老实实用放大电路+relay吧
f*0
23 楼
the problem is the 0.5v threshold. very few amps will be trigger by that
kind of voltage.
to "amplify" it, you will have to solve the power supply issue for such a
voltage.
the best alternative I think is a germanium transistor; then a comparator (
but you will have to solve interference issue so the comparator doesn't flip
accidentally).
kind of voltage.
to "amplify" it, you will have to solve the power supply issue for such a
voltage.
the best alternative I think is a germanium transistor; then a comparator (
but you will have to solve interference issue so the comparator doesn't flip
accidentally).
h*e
24 楼
pmos input can handel 0-1V easily with 3V or 5V supply.
Using a differential PMOS inputs amplifier with negative-side set to 0.25V,
0 input will leads to ~5v output and 0.5V input will leads to ~0V ouput.
Althought gain could be low, it is good enough to make logic transition.
Using a differential PMOS inputs amplifier with negative-side set to 0.25V,
0 input will leads to ~5v output and 0.5V input will leads to ~0V ouput.
Althought gain could be low, it is good enough to make logic transition.
f*0
25 楼
mosfet typically has Vgs threshold at 3.5v, p-channel or n-channel. using it
always requires setting up a voltage, which I am not sure is superior.
always requires setting up a voltage, which I am not sure is superior.
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