Too stooped to live: why can't I build a regulated 9V ps for my DD500

[Lizard King]

I have a 12V unregulated AC-DC circuit that provides 450mA.  I add a LM7809 with the proper caps - even oversized the caps to .3uF & .1uF.  The output measures 9V DC and still nothing.  The led on my circuit board flickers but won't turn on the DD500.  I have the proper polarity...proper voltage....proper current....no workie.....do i need to do something to further "regulate" the power supply?

thanks.....

[antonis]

Although I think that you haven't a "regulation" problem (typical load regulation for 200mA is about 4mV for LM7809 with 330nF & 100nF caps..) try to oversize caps to 470μF (+100nF ceramic) & 47μF respectively.

[Lizard King]

Thanks.  I was just ready to update my post.

I found a schematic floating around the web (I looked harder today than I did yesterday, LOL).
It looks like Boss uses a 1N4148 between pin 2 & ground, a 1000uF cap on input and 220uF cap on output....so I was way undersized if I get the right schematic.

I'll try that tonight and report back!

Thanks again!

[TejfolvonDanone]

The 7809 has got overcurrent and overtemperature protection. The flickering LED indicates that it turns on and off rapidly so you got into the foldback current limiting or it overheats. So either you are using a LM78l09 which is in a TO92 package (and has a 100mA current limit) or you wired incorrectly the power supply connection into the DD500 (mixed up the 9V and GND).

[duck_arse]

expect 9V6 output, from the diode-jacked-up ground. does the regulator still supply 9V when connected to the DD thing?

[Lizard King]

The 7809 has got overcurrent and overtemperature protection. The flickering LED indicates that it turns on and off rapidly so you got into the foldback current limiting or it overheats. So either you are using a LM78l09 which is in a TO92 package (and has a 100mA current limit) or you wired incorrectly the power supply connection into the DD500 (mixed up the 9V and GND).

Using an L7809CV TO220 rated at 1.5A.  I have some TO92 packages and I'm definitely not using those.  I checked the polarity dozens of times before and after I plugged into the Boss.  Everything I read says the Boss is neg center pin...which I have. 

[Lizard King]

expect 9V6 output, from the diode-jacked-up ground. does the regulator still supply 9V when connected to the DD thing?

Boss actually rates their PSA at 9.6V.  The one thing I didn't measure was voltage after plugging it in, D'OH.

I have some things to try tonight.

Thanks everyone for the input.

[Lizard King]

Not sure if it was the diode or the bigger caps but I got it to fire up my DD-500 using a 470uF cap at input, 1N4148 diode between ground & 100uF cap at output of the 7809.

Thanks for the help!!!

[antonis]

Not sure if it was the diode or the bigger caps

Probably both..

Diode raised the output voltage to 9.6V and bigger caps regulated (better filtering) this voltage..

[Lizard King]

Not sure if it was the diode or the bigger caps

Probably both..

Diode raised the output voltage to 9.6V and bigger caps regulated (better filtering) this voltage..

Probably the caps.  One other solution I tried was an LM317 with resistors sized to produce 9.6V.  But I didn't oversize any caps on that fail.

Thanks again!