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| Fig. 2(a) --- A1 LAYOUT |
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VALUE |
PURPOSE |
R1 |
50Ω for most applications |
A1 base current |
C1 |
≥ 1 nF (value not critical) |
bypass input noise from R1 |
R2 |
200Ω - 1KΩ (FS once) |
sets gain of A1 & hence start of logging |
C2 |
1– 4pF (FS once) |
cancels effect of input capacitance |
R3
C3 |
0.3-10K
1- 3 pF |
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FS (once)
if needed |
used to remove small overshoots |
C4 |
0 – 4pF (FS once) |
A1 comp cap |
R4 |
~ 150K (200K pot) |
corrects negative output offset of A1 |
RLIN |
~ 100 - 300K (FS once) |
linear extension corrects for detector roll off |
DT1
RT0
RT1 |
- 30K
~ 5K |
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FS (app notes) |
tempco as shown will correct for A1 out going negative as T↑
See App Notes |
RV1, RV2, CV1, CV2 |
(FS once) |
recovery nets |
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NOTE: FS = Factory Select; (the correct component value must be ascertained for each replicated unit).
FS (once) = the correct component value needs to be factory- selected only once for a given layout; subsequent units will use the same component value (assuming reasonable detector matching). |
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6 February 20, 2008 |
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