boops Posted October 3, 2008 Report Share Posted October 3, 2008 Hi,all,i am looking for a shematic to build a -2,6 v(lcd negative contrast ) with the 5v core psu,thanksI 've a made a newbie error when i 've ordered my 2 lcd at voti..be careful lcd 14 is not the must, take lcd 22 Boops Quote Link to comment Share on other sites More sharing options...
boops Posted October 3, 2008 Author Report Share Posted October 3, 2008 Ping has given me this link http://www.modthebox.com/lcdhowto.shtmlthanks but how can i have 2,6v ? Quote Link to comment Share on other sites More sharing options...
/tilted/ Posted October 4, 2008 Report Share Posted October 4, 2008 The LCD derives its contrast voltage using a pot (P2) connected across +5V and GND (Vdd and Vss). The wiper of the pot is then connected to the Vo Contrast pin on your LCD.Normally LCD contrast voltages are in the range 2V - 3.5V.To get -2.6v, build the circuit linked by Ping, and wire your pot (P2) across -5V and GND. The wiper of the pot connects to Vo as normal.Be sure to disconnect the +5V terminal of your pot before connecting it to -5V, to avoid smoke... Quote Link to comment Share on other sites More sharing options...
stryd_one Posted October 4, 2008 Report Share Posted October 4, 2008 Also there are several hits using the search terms I gave you last night of schems using a 766* ICshttp://www.midibox.org/forum/index.php/topic,3540.msg23987.html#msg23987 Quote Link to comment Share on other sites More sharing options...
boops Posted October 4, 2008 Author Report Share Posted October 4, 2008 thanks folks Quote Link to comment Share on other sites More sharing options...
ping- Posted October 4, 2008 Report Share Posted October 4, 2008 Ping has given me this link http://www.modthebox.com/lcdhowto.shtmlthanks but how can i have 2,6v ?Uhmn..i didnt give you that link :)I dont know who did, but it wasnt me.. i have never seen that link before :D Quote Link to comment Share on other sites More sharing options...
boops Posted October 4, 2008 Author Report Share Posted October 4, 2008 ::) sorry it's doug W. Quote Link to comment Share on other sites More sharing options...
boops Posted October 4, 2008 Author Report Share Posted October 4, 2008 hi,i do the job... :o it works ;magic electronic!!! An advice: put the trim p2 on a separate veroboard with the IC 7660 and Caps; be careful with the caps polarity and put off the 18F452...now i attack the opl3 -core connections :P Good night and best regards . Quote Link to comment Share on other sites More sharing options...
stryd_one Posted October 5, 2008 Report Share Posted October 5, 2008 [me=stryd_one]does the "it's working" dance[/me]boops I hope you can share more details of your solution... you're not the first to have this problem, and I'm sure others will be in the same situation again ;) Quote Link to comment Share on other sites More sharing options...
/tilted/ Posted October 5, 2008 Report Share Posted October 5, 2008 Good to hear.Well done. Quote Link to comment Share on other sites More sharing options...
boops Posted October 5, 2008 Author Report Share Posted October 5, 2008 stryd i 've done exactly that is wrote on the post and use a little my brain ,a paper and a pen too;)f Quote Link to comment Share on other sites More sharing options...
boops Posted October 5, 2008 Author Report Share Posted October 5, 2008 more explanations:-printed the shema with the IC 7660 ,and caps -buy the parts,don't forget the ic socket for the 7660 (or equivalent)-pull off the ics of the core-cut a little piece of veroboard and make a hole (3mm)to install on one hole of the core pcb-desolder with (pompe a dessouder) the P2 (trim on the right on the core,which control the contrast)-build the shematic http://www.modthebox.com/lcdhowto.shtml be careful with caps polarity ,take the +5v and ground on the core where the P2 was soldered,test short cuts,and polarity ,you should have -5v beetween ground and pin 5 of the ic 7660 -ok ,courage ,now solder the P2 on the little veroboard and see the shematic below: -control the negative voltage with the P2 trim.. BRAVO Boop'sP051008_13.22.JPGP051008_13.22.JPG Quote Link to comment Share on other sites More sharing options...
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