[Icy006]

Great info, thanks.

jar pointed out to me that Headroom sells an inexpensive power brick used in many of their amps that puts out +15/-15 volts. If it can handle the current draw and puts out relatively clean power, I think I might be going this route, as it lets me case the Dynalo in something transportable.

 

[dgardner]

I popped open one of my ELPAC WM071-1950 wall warts. Inside is a transformer, rectifier, 7815, 7915 and a 1000uF output cap on each. Not bad for starters... You only need about 200mA per rail max for a dynalo. Typical is about 150mA per rail if built to spec.

 

[Icy006]

Hrm, looks like the elpac WM071-1950-D5 can handle 240mA per rail, nice. In stock at Newark for about forty smackers. I've had good luck with my WM080 24v so I think I'll check this out. Thanks Dan.

 

[jar]

The headroom power supply is also rated at 240 mA per rail. It's labeled Advanced Power Solutions APS48-ER125. I can't find this model on Advanced Power Solutions' web site for some reason.

 

[bg4533]

The Headroom PSU looks nice since it has a cord that plugs into the wall instead of just a huge brick. It can be difficult to find a place to plug in the Elpac.

 

[CB600F]

Hi there,

<< Finally I started an electronics project again. It has been a while. >>

Has anyone been fiddling around with the dynalo and the SWCAD III Spice simulator? (Or any other spice simulator for that matter)
I have just started with my first simulations and it seems to simulate the amp pretty well. I tried some other transistors like the bc547b; no shocking differences there. I thought the opamp would make a difference, but after adjusting simulation resolution there was no noticeable difference.

Regards,

David

PS. I also posted this message on the construction thread

 

[dgardner]

The op amp is the dc offset servo. It should not have any real impact on the frequency respsonse or any other part of AC Analysis.

 

[Garbz]

Indeed the DC servo kicks in under 1 or 2 Hz doesn't it? It should not modulte the signal audibly at all!

 

[bg4533]

Quote:

Originally Posted by Garbz Indeed the DC servo kicks in under 1 or 2 Hz doesn't it? It should not modulte the signal audibly at all!

.05Hz according to the original Headwize article.

 

[CB600F]

Quote:

Originally Posted by dgardner The op amp is the dc offset servo. It should not have any real impact on the frequency respsonse or any other part of AC Analysis.

I know what the opamp is for, but I wanted to know if it added an AC component to the circuit: apparently not. In my simulation the DC offset servo isn’t working at all. I tried different LED’s and so on; no result at all. I’ll be working on that for now. I haven’t been working with electronics for quite some time, so I’ll probably goof up once in a while.

I'm probably doing something wrong with the simulation.

 

[Nospam]

Quote:

Originally Posted by bg4533 The Headroom PSU looks nice since it has a cord that plugs into the wall instead of just a huge brick. It can be difficult to find a place to plug in the Elpac.

That's why I bought a bunch of these:
http://www.cyberguys.com/templates/s...search=&child=

or if you want higher quality:
http://www.cyberguys.com/templates/s...search=&child=

 

[dgardner]

Another thread supporting construction questions on the Dynalo Rev C project is here.

 

[Icy006]

Quote:

Originally Posted by jar The headroom power supply is also rated at 240 mA per rail. It's labeled Advanced Power Solutions APS48-ER125. I can't find this model on Advanced Power Solutions' web site for some reason.

I got this power supply to use with my Dynalo.

Just a heads-up to those who would do the same thing: it uses a 5-pin din connector, but the pins are in a 270 degree configuration, not the more common 180 degree layout.

I ordered this 180 degree one by mistake, which does not work. I should have ordered something more like this 270 degree one .

 

[GeeKo]

Hi all
I have problem with finding good 24.9 ohm resistors   R23 - R30, R53- R60
May I replace them with different value ??

 

[bada bing]

Mouser shows a few hundred of both RN55 and RN60 Vishay/Dale (1/8 watt and 1/4watt) in stock.
http://www.mouser.com/ProductDetail/Vishay-Dale/RN55D24R9FB14/?qs=sGAEpiMZZMu61qfTUdNhGy2XqlsoYCVGaHnL7ELbeOo%3d
http://www.mouser.com/ProductDetail/Vishay-Dale/RN60D24R9FB14/?qs=sGAEpiMZZMu61qfTUdNhG%252bW6BexHzDUms0DkBv%252bx1ME%3d
 
If you're using a DGardner -now AMB- provided board, the 1/4watt RN60 fit fine, but there is no electrical reason to not use the smaller 1/8watt RN55.
 
You really used the way-back machine to dig up this post, hehe.