Author Topic: 9V to +-14v  (Read 6514 times)

armdnrdy

Re: 9V to +-14v
« Reply #100 on: February 14, 2018, 12:57:25 AM »
If you are referring to changing the circuit voltage with pots....
I believe that I mentioned early on that deviating from the stock CE-1 voltage of +14/0/-14 would change the LFO and the clock from the original.
It sounds like that is what you are encountering when you adjust the voltage.
More width may sound good in the vibrato setting...but not so much in the chorus.
If it sounds good to you....then it is good!
I just designed a new fuzz circuit! It almost sounds a little different than the last fifty fuzz circuits I designed! ;)

nickbungus

Re: 9V to +-14v
« Reply #101 on: March 09, 2018, 06:10:33 AM »
I've been messing with this again recently and I've been having great results with the MC34063.  The results have been much better than the LT1024.  (Less drop, ripple and noise)

Is there anyway I can get both +14 and -14v out of one MC34063?  The inductors are relatively large and having one less chip would free up some room.
No, they are not jumpers, they are just very, very low value resistors.

Rob Strand

Re: 9V to +-14v
« Reply #102 on: March 09, 2018, 06:38:59 AM »
Quote
s there anyway I can get both +14 and -14v out of one MC34063? 
There's a couple of applications notes mentioned at the top of  the datasheet.
Here's one.  You can see a +/- supply example.   The + is regulated by the switcher and the - is made-up then regulated linearly.
http://www.intusoft.com/onsemipdfs/AN920-D.pdf

Have a poke around at other switch-mode chips.  There's many tricks to get a + and - rail.
I think some of the Linear-tech devices show some more examples.

Quote
The inductors are relatively large and having one less chip would free up some room.
The switch frequency looks quite low by todays standards (200kHz pretty common). 
The low frequency pushes the inductor size up.
The mind often distorts without gain.

nickbungus

Re: 9V to +-14v
« Reply #103 on: March 09, 2018, 11:00:45 AM »
Thanks Rob.  I've had a quick look at the link and I dont currently (or voltagely !! :icon_redface:) understand, I'll have a good read tonight in bed and see if I can expand my knowledge.
« Last Edit: March 09, 2018, 11:24:14 AM by nickbungus »
No, they are not jumpers, they are just very, very low value resistors.

Rob Strand

Re: 9V to +-14v
« Reply #104 on: March 09, 2018, 06:48:35 PM »
Quote
Thanks Rob.  I've had a quick look at the link and I dont currently (or voltagely !! :icon_redface:) understand, I'll have a good read tonight in bed and see if I can expand my knowledge.
The circuit I was looking at was fig 31.  I guess it's more of an example that it can be done.  That circuit is still a bit messy.  I know some of the linear technology applications notes and datasheets have other often cleaner examples.

The high-end Yamaha basses used ICL7662/ICL7660 with two inductors to get +/- rails.   They are quite low frequency, so require largish inductor values.  People did complain of the 10kHz whine - so not recommended.

Shielded inductors are a good investment to prevent noise problems.
The mind often distorts without gain.