HI
Can someone run me down a few reasons why an LFO might not "work"?
Im talking about a Op amp based LFO. assuming the power, bias, and GND are all connected, what might cause it to not work?
For detail, I am building another Lovetone Flange and the LFO isnt spinning :(
ive tested all traces for continuity, checked parts values, changed the Op amp chip, tried different op amp types etc.
Ian
Couple of suggestions:
1) Check the proper wiring on ALL of your jacks. Especially the Trig/Gate jack
2) Check to ensure that you have the correct semis in Q14 and Q15 (BC307B and J113 respectiively)
3) Check proper continuoty for SW1.
Good Luck! ;D
Quote from: Govmnt_Lacky on November 10, 2014, 03:40:44 PM
Couple of suggestions:
1) Check the proper wiring on ALL of your jacks. Especially the Trig/Gate jack
2) Check to ensure that you have the correct semis in Q14 and Q15 (BC307B and J113 respectiively)
3) Check proper continuoty for SW1.
Good Luck! ;D
cheers Gov
i havent wired the jacks yet but ive grounded the trigger wires, so that does 1)
2) I dont. I have switched the JFET for 2n5457, and the BC307B i only have a BC560 which should be compatible. Any thoughts on that?
https://www.fairchildsemi.com/datasheets/BC/BC556.pdf
3) switches wired properly.
pretty sure I used the same transistor subs previously with no issue, definitely the Jfet
with that said I have ordered the proper part replacemetns which will arrive soon
2N5457 and J113 respond differently at low freq... my 3046vco's won't go LF with 2n5457, they are meant for 113's. Suspect that is your problem.
Quote from: alanp on November 10, 2014, 04:18:21 PM
2N5457 and J113 respond differently at low freq... my 3046vco's won't go LF with 2n5457, they are meant for 113's. Suspect that is your problem.
ok i will replace all those. I could have sworn I used the 5457's last time...
Quote from: alanp on November 10, 2014, 04:18:21 PM
2N5457 and J113 respond differently at low freq... my 3046vco's won't go LF with 2n5457, they are meant for 113's. Suspect that is your problem.
however, still, I used 2n5457 in place of the j113 in the wobulator too, as its used in that part of the circuit to enact the trig/gate same as the flanger, and it was fine then...
The LFO here is generated from the op amp unless I can be eduicated, so I dont see why the JFET are involved....
can you confirm?thanks
edit - i may be talking shit, just checking my email for "j113" reveals I did order some !
hurrah
just subbed Q15 for a MPF102 and the oscillator is now working
thanks hive mind
no thanks to my alzheimer mind
I love it when a plan comes together!
(http://i.ytimg.com/vi/ZqPlcu8Sivs/maxresdefault.jpg)