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Transcription

1 Oscillaors. Thory of Oscillaions. Th lad circui, h lag circui and h lad-lag circui. Th Win Bridg oscillaor. Ohr usful oscillaors. Th 555 Timr. Basic Dscripion. Th S flip flop. Monosabl opraion of h 555 imr. Asabl opraion of h 555 imr. Th VO Volag onrolld Oscillaor. Puls Widh Modulaion. Puls Posiion Modulaion. amp Gnraor.

2 s cos X,s cos This is calld a LEAD circui sc h pu volag prcds lads h pu volag by a phas which dpnds on h frquncy. I is also a high pass filr sc i allows high frquncis o pass and blocks dc signals.

3 ,s cos A 0 90

4 s cos X X,s cos This is calld a LAG circui sc h pu volag succds lags h pu volag by a phas which dpnds on h frquncy. I is also a low pass filr sc i allows low frquncis and dc signals o pass and blocks high frquncy signals signals.

5 ,s cos A 0 90

6 Z Z Z Z Z 3 Z Z X // X This is calld a LEAD LAG circui and i is h fdback circui of a Win bridg oscillaor. W will xam is frquncy dpndn bhaviour.

7 9 9 s cos Z Z Z 9,s 9 3 cos

8 A 9 3 Volag ga of a LEAD LAG circui as a funcion of frquncy. Th circui has a rsonan frquncy whr h volag ga is maximizd. r

9 cos 3 9,s r 0 90 Phas diffrnc bwn h pu and pu signals a a LEAD LAG circui. A h rsonan frquncy h pu signal is phas wih h pu.

10 Win Bridg oscillaor. V f r π - A -V L

11 Th 555 Ingrad ircui imr is an I ha can run wo mods. Eihr monosabl whr i has only on sabl sa or asabl whr i has no sabl pu sa. In h monosabl mod h 555 afr i rcivs an xrnal riggr puls i changs is sa from LOW o HIGH bu sc his is no a sabl sa afr som im i maks a ransiion back o low from high. Thrfor i producs an pu puls of fixd duraion W. Anohr nam for h 555 oprag h monosabl mod is monosabl or on-sho mulivibraor. Th 555 conncd as an asabl mulivibraor has no sabl sas bu i oscillas bwn wo pu sas producg a priodic rcangular signal a sris of rcangular pulss. Anohr nam for h asabl opraion of h 555 is fr-runng mulivibraor. An xampl of a bisabl mulivibraor is h S Flip Flop. I has wo sabl pu sas and i lachs o an pu sa dpndg on is pu. I is a basic lcronic mmory cll and w will dscrib is opraion.

12 Th S Flip Flop has on powr supply V wo pus S SET, ESET and wo complmnary pus Q and Q /. Th wo pus canno b boh HIGH or boh LOW a h sam im. Whn Q is high Q / is low and vic vrsa.by applyg a high puls a h S pu w can driv h lf ransisor o sauraion. This will mak Q / LOW and hrfor i will driv h righ ransisor o cuoff makg hrfor Q high. Th sa is sabl vn if w rmov h S high signal. If w impos a high signal a h pu h opposi will happn. W will driv h righ ransisor o sauraion and his will driv h lf ransisor o cuoff. Th sa will prsis vn afr h rmoval of h HIGH puls and w will hav a HIGH Q / and a LOW Q. I is prohibid hough o hav boh pus HIGH sc his will produc undrmd rsuls. If w kp boh pus LOW h flip flop will maa is las sa. I xhibis mmory and i is h basic cll of lcronic mmory.

13 This is a rough skch of h 555 imr P 5 is usd o s h pu frquncy whn h 555 imr is oprag h asabl mod. P 5 is s aciv by conncg i o ground via a capacior. P 4 rss h pu volag o zro. I can b s aciv by conncg i o V. P is h riggr volag whn h imr works h monosabl mod. P is conncd o h lowr comparaor and whn is signal bcoms lss han h LTP V /3 maks h lowr comparaor o produc an pu signal. P 6 is h hrshold. Whn h hrshold is largr han Th UTP V /3 h uppr comparaor producs a HIGH pu. Sc h hr rsisancs of h volag dividr ar qual w hav: UTP V /3 LTP V /3

14 This is h conncion of h 555 h monosabl opraion.whn firs powrd h xrnal capacior is chargd and p 6 is a V /3. Sc P is HIGH Th wo comparaors will produc S and 0 which will s h flip flop a Q and OUT 0. High Q will saura h ransisor and h xrnal capacior will discharg islf hrough h ransisor sg p 6 o ground and S 0 which has no ffc a h pu of h flip flop. A shor riggr signal a p from low o high will s S 0, ha will produc OUT and Q 0 which will cu h ransisor off. Th capacior will onc mor sar chargg islf and whn h volag a p 6 bcoms V /3w will hav S, 0 and h flip flop pu will onc mor b Q, OUT 0. Th duraion W of h HIGH pu sa is qual o h amoun of im i will ak h xrnal capacior o charg islf up o V /3. I can b provn ha W. Exrnal and conrol h duraion of h asabl puls.

15 In h monosabl opraion whn h TIGGE signal a PIN high h pu is low and h capacior is kp dischargd via h ransisor which is acg as a virual shor bcaus i is kp saurad. If a shor puls high o low is fd o h p h is gog o bcom high, h ransisor is gog o b cu off and h chargg of h capacior will sar as shown h figur. For as long as h capacior is bg chargd h pu is gog o b high and h ransisor cu off. Whn h ransisor volag rachd V /3 will bcom low and h ransisor saurad. Th 555 will fall o is sabl sa.

16 Proof of h W. formula for h asabl opraion of h 555 imr. Th im dpndnc of h chargg of h xrnal capacior is: V V V V W ln 3. 3 W P 5 ONTOL is conncd o ground via a capacior o prvn sray m nois o rfr wih h circui opraion. P 5 his way bcoms aciv. P 4ESET is conncd o V and his way is aciv durg his opraion of h 555 imr. For h asabl opraion of h 555 imr wo xrnal rsisors and on capacior ar rquird. P h riggr and p 6 h hrshold ar id oghr, o h ground via an xrnal capacior and o h p 7 discharg via an xrnal rsisor. P 7 is also conncd o p 8 h powr supply V via anohr xrnal rsisor.h capacior is conuously chargd and dischargd sg h flip flop a S 0 and S0, conscuivly. Whn h capacior is chargd i is h im consan is and whn dischargd h im consan is. Th lows capacior volag is h LTP V /3 and h highs is UTP V /3.

17 Iniially h capacior is chargd up o V /3 wi a im consan and S,0 ha s OUT 0 and h ransisor o dp sauraion. Th saurad ransisor dischargs h capacior wih a im consan down o LTP V /3 ha s S0,, OUT and h ransisor o cuoff. Th capacior discharg sops and h chargg sars all ovr. OUT durg h capacior chargg im and OUT 0 durg is dischargg im.

18 In an circui wih pu consan dc volag V, h volag a h capacior is givn by h quaion. V V 0 V V Whn h capacior chargs islf V 0 V /3, V V and. Th chargg im W is: V W V W 3 V 3 ln V W Whn h capacior dischargs islf V 0 V /3, V 0 and. Th dischargg im is: V W V V V ln Th priod of h wavform is W T T ln 0.693

19 Whn h 555 chip is oprag as Volag onrolld Oscillaor or VO i is conncd as an asabl mulivibraor wih h only diffrnc ha p 5 ONTOL is no idl by bg conncd o ground via a capacior bu i is conncd o a poniomr which is conncd o h powr supply V. Thrfor h V con volag of p 5 can vary from 0 o V. call ha p 5 is dfg h UTP of h 555 firs comparaor. Th xrnal volag V con ovrrids h dfaul UTP V /3 and LTP V /3 and ss hm o UTP V con and LTP V con /. Th capacior chargs and dischargs islf from LTP o UTP and vic vrsa, oprag onc mor h asabl configuraion. By usg: V 0 V V W can fd V W T W V ln V ln 0.5V V con con

20 In h STAT and ESET circui h 555 imr is conncd h monosabl configuraion. Whn h swich a PIN is prssd a TIGGE signal producs an pu puls of fixd duraion. This puls may driv an alarm or FET or buzzr. Hr h figur i drivs an LED. Th swich a PIN 4 acs as a ESET buon o rs h imr pu a LOW cas ha h pu signal lass oo long.

21 In h ALAM circui h 555 imr is conncd h asabl configuraion. Normally h swich a PIN 4 is closd and h imr has h ESET p aciv. Whn h swich is dprssd opn a rcangular priodic wav ra is gnrad which h figur drivs a sirn. Th alarm can b rs by prssg h PIN 4 swich on mor. Whn h swich a PIN is

22 In Puls Widh Modulaion h imr is conncd h monosabl configuraion. A priodic TIGGE puls is fd a PIN and is priod dfs h priod of h pu rcangular pulss. A PIN 5 an ac pu signal is suprimposd on h dc UTP V /3. Th pu rcangular pulss hav a consan priod bu hir widh dpnds on h sananous UTP whn h riggr puls a PIN arrivd.

23 In h Puls Posiion Modulaion h 555 imr is conncd a h asabl configuraion. A PIN 5 an ac pu signal is suprimposd on h dc UTP V /3. Th pu squnial rcangular pulss hav consan spac bwn hm h discharg im of h capacior ln. Th widh of ach puls dpnds on h sananous UTP. Noic h absnc of clock.

24 In an circui wih pu consan dc volag V, h volag a h capacior is givn by h quaion. V V 0 V V Whn h capacior chargs islf V 0 LTPUTP/, V V and. Th fal volag of h capacior will b VWUTP and h chargg im will b: V W Whn h capacior dischargs islf V 0UTP, V 0,.and V LTPUTP/. Th dischargg im is: V W UTP UTP UTP ln UTP V V UTP ln V 0.5 UTP Th priod of h wavform is W T W V T ln 0.693

25 Whn h 555 imr is configurd as a ramp gnraor i is conncd h monosabl configuraion bu h chargg of h capacior now is via h mir currn of a ransisor. Th ransisor is biasd such a way ha i dlivrs consan currn I E V -V E / E. Th V E is drmd from V E -V B 0.7V and V B is drmd from h, volag dividr. urrn I E is chargg h capacior and h capacior is bg dischargd sananously via h saurad ransisor sid h 555 I. Th pu now is no from p 3 any mor bu from ps 6 and 7 shord oghr. Whn a riggr arrivs h capacior sars chargg islf and h pou volag is V I /. Th duraion of ha ramp lik volag puls is givn by h quaion: V UTP 3 V W 3I I W