求救(有關二極管)幫我計呢兩題數~急急急~

2010-03-12 3:58 am

http://i926.photobucket.com/albums/ad110/alantse30/-2.gif

Q1)圖1↑
Calculate the voltages with respect to ground at point A and B.
(Assuming D(1) and D(2) are both silicon diodes and V(D)(ON)=0.7V)

http://i926.photobucket.com/albums/ad110/alantse30/-1.gif

Q2)圖↑

Assuming the V(F) of D1,D2,D3 and D4 are 700mV and the transformer's turn ratio(primary : secondary) is 10:20, the peak input voltage Vp is shown below, calculate:
i) The Vrms of the primary winding

ii)The Vrms and Vp(sec) and secondary winding of the transformer, show your answer in V.

iii) The peak voltage and average voltage across R(L)

iv) The peak Inverse Voltage across the diode.

更新1:

ii)The Vrms and Vp(sec) and secondary winding of the transformer, show your answer in V. = Vrms(S) = Vrms(P) x 0.707 = 21.2V = ≤21V Vrms(P)既然係10.6, Vrms(S) = Vrms(P) x 0.707=10.6 x 0.707 =7.5V 如果計到係21.2V,應該係用Vp(S)=30 x 0.707 =21.2V 另外,可唔可以教下我iii) The peak voltage and... 如何計到=30V 我唔係好識,請博士教下我!!萬分感激

回答 (1)

用戶8430

2010-03-12 7:23 am

✔ 最佳答案

圖片參考：http://i926.photobucket.com/albums/ad110/alantse30/-2.gif

由於你冇註明二極管號碼只係話電壓降V(D)0.7V, 而且電路冇任何接地, 電源電壓有10V, 電阻串聯後有2KΩ, 電流只有0.005A, 但係R2後有負電壓 -0.7V, 你問A點同B點對地各有幾V, 答案係0V。

圖片參考：http://i926.photobucket.com/albums/ad110/alantse30/-1.gif

呢個電路圖冇電容, 唔會有峰值, 而且有電壓降因爲有負載50Ω, 比率10:20(初級10次級20), 初級電壓(峰值)Vp=15V, 次級應該係Vp=30V, 經過二極管後電阻負載50Ω,

i) The Vrms of the primary winding
= Vrms = Vp x 0.707 = 10.6V

ii)The Vrms and Vp(sec) and secondary winding of the transformer, show your answer in V.
= Vrms(S) = Vrms(P) x 0.707 = 21.2V = ≤21V
= Vp(S) = 15 x 2 = 30V = ≤30V

iii) The peak voltage and average voltage across R(L)

= ≤30V

iv) The peak Inverse Voltage across the diode.

????? 已經產生諧波 Harmonic 計唔掂咗。

2010-03-12 22:24:28 補充：
Assuming the V(F) of D1,D2,D3 and D4 are 700mV and the transformer's turn ratio(primary : secondary) is 10:20,

in diagram http://i926.photobucket.com/albums/ad110/alantse30/-1.gif

input Vp : 15V the transformer ratio is 10 : 20, so output = 15Vp = output = 30Vp 啦

2010-03-12 22:29:06 補充：
sorry 呢題計錯

= Vrms(S) = Vp(S) 30V x 0.707 = 21.2V = ≤21V

= Vp(S) = Vp(P) x 10 : 20 = 15V x 2 = 30V = ≤30V

2010-03-12 22:29:48 補充：
= Vp(S) = Vp(P) x 10 : 20 = 15V x 2 = 30V = ≤30V

= Vrms(S) = Vp(S) 30V x 0.707 = 21.2V = ≤21V

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