Samvinna
LIST
FEGURÐ OG VELLÍÐAN
HANDVERK
MENNING OG SAGA
SKEMMTUN
UMHVERFI
MATUR OG DRYKKUR
ÖFUGVERKFRÆÐI
VÍSINDI
ÍÞRÓTTIR
TÆKNI
KLÆÐANLEG TÆKNI
Function Generator: Resistance-Capacity Tuned Audio Oscillator with Lamp Amplitude Control (Hewlett, US 2,268,872, 1942)
The first Hewlett-Packard product: a test oscillator tuned by resistors and capacitors instead of coils. Two valve amplifiers feed their output back to their input through a series and a parallel R-C pair, which passes only one frequency in phase, so the circuit oscillates there. A second, negative feedback path through a small lamp holds the amplitude steady: as the swing grows the lamp warms, its resistance rises and the gain falls. One dial covers ten to one in frequency.
Result: a sine-wave signal generator covering 20 to 20,000 cycles in three ranges, about 0.25 % distortion.
Source: W. R. Hewlett, US 2,268,872 (1942). Unknown: valve types and component values. Picture: the patent drawing.
Lengra kominn
Unknown
Leiðbeiningar
1
1
Build the two-stage amplifier
Build the two-stage amplifier
Wire two amplifying valves in cascade with resistance-capacity coupling, the first's anode to the second's grid, run as class A amplifiers. Not given: valve types, values, the supplies. Ours: pentode valves in sockets.
Efni fyrir þetta skref:
Pentóðulampi2 stykki
Lampasökkull2 stykki
Viðnám1 sett
Þéttasett1 coupling and by-pass
Álkassi1 case
Lóðtinsvír1 as neededNauðsynleg verkfæri:
Lóðbolti2
2
Fit the tuning network
Fit the tuning network
From the second valve's anode, through a coupling capacitor, feed back to the first valve's grid through a resistor R1 in series with a variable capacitor C1, with a resistor R2 and variable capacitor C2 from the grid to ground. Make R1 = R2 and C1 = C2: the frequency is then 1/(2 pi R C), set by the capacitors, giving 10 to 1 on one dial. For the capacitors use a four-gang tuning capacitor with its sections paired in parallel. Switch three sets of resistors in for the ranges 20-200, 200-2000 and 2000-20,000 cycles. Ours: a rotary switch.
Efni fyrir þetta skref:
Breytilegur þéttir (loftþéttiefni)1 four-gangViðnám1 three sets of R1, R2
Snúningsrofi1 range switchNauðsynleg verkfæri:
Lóðbolti
Skrúfjárnasett3
3
Fit the lamp feedback and use it
Fit the lamp feedback and use it
From the same output, through the coupling capacitor, feed back to the first valve's cathode across a resistor R4 and a small incandescent lamp R3. As the oscillation grows, the lamp heats, its resistance rises, the negative feedback increases and the gain falls, so the amplitude settles below the point of grid current with no clipping. The negative feedback also steadies the gain against valve and supply changes. Take the output from the terminals; Hewlett's test unit held its output within about 10 % over 20-20,000 cycles, with about 0.25 % distortion and under 0.1 % frequency shift with supply changes.
Efni fyrir þetta skref:
Ljósapera1 small incandescent lampViðnám1 R4
Tengipóstur2 outputNauðsynleg verkfæri:
JafnstraumsgjafiLóðboltiEfni
10- 2 stykkiStaðgengill
- 2 stykkiStaðgengill
- 1 R4Staðgengill
- 1 coupling and by-passStaðgengill
- 1 caseStaðgengill
- 1 as neededStaðgengill
- 1 four-gangStaðgengill
- 1 range switchStaðgengill
- 1 small incandescent lampStaðgengill
- frá$0.51
Þessi teikning býr til
CC0 opinbert ríki
Þessi teikning er gefin út undir CC0. Þér er frjálst að afrita, breyta, dreifa og nota þetta verk í hvaða tilgangi sem er, án þess að biðja um leyfi.
Studdu smiðinn með því að kaupa vörur í gegnum teikningu hans þar sem hann fær þóknun smiða sem seljendur ákvarða, eða búðu til nýja endurskoðun á þessari teikningu og tengdu hana sem tengingu í þinni eigin teikningu til að deila tekjum.