power supply modding help needed

[drinkies]

can anyone help with modding a dse d-3800 psu(3-15v,25a) to an adjustable constant current rectified power supply for aluminium anodising

[Reschs]

Circuit of existing unit needed before anyone can comment.

[tristen]

Circuit of existing unit needed before anyone can comment.

I located the circuit and manual at mods.dk but haven't had a chance to look at it yet.

For those interested, I've upladed it to .

[Uncle Fester]

Somebody kindly marked over the regulator IC.
If we could identify that IC a data sheet search might help further if the print is still visible on the IC.
The current is determined by R3 so if you use a higher resistor the regulator IC will limit at a lower current but that is not a good way of regulating it. Althougth you could solder 2 or three 0.1 Ω 5W resistors in series to R3 and short them with switches for a very rough regulation.
Adjusting VR 2 might have also have some influence on the maximum current, which you could test by carefully adjusting it at maximum load.

Better if we had the data sheet of the IC.

[Gyro]

Somebody kindly marked over the regulator IC.
If we could identify that IC a data sheet search might help further if the print is still visible on the IC.
The current is determined by R3 so if you use a higher resistor the regulator IC will limit at a lower current but that is not a good way of regulating it. Althougth you could solder 2 or three 0.1 Ω 5W resistors in series to R3 and short them with switches for a very rough regulation.
Adjusting VR 2 might have also have some influence on the maximum current, which you could test by carefully adjusting it at maximum load.

Better if we had the data sheet of the IC.

The IC is a LM723, does anyone know how the overload LED section works, my power supply intermittently on switch on, the overload LED comes on and has no O/P, comes good after 5 minutes or so?

[Reschs]

The IC monitors the voltage across a low value resistor via pins 2 & 3, with possibly a pot to adjust the limit.
If it comes good after a warm up period, look for a leaky capacitor on the output side.

[BCNZ]

I located the circuit and manual at mods.dk but haven't had a chance to look at it yet.

For those interested, I've upladed it to .

Dead link. Could you possibly upload it again?

I'd like to look more at this, as anodising (and rust removal which uses a similar process) is of interest to me.

[tristen]

I don't have it on this computer, but you can find and download it yourself by searching the mods.dk website.

Here, open the following link and type 3800 into the search box .

Site membership is necessary but is not at all difficult and won't break the bank.

It's an useful site to bookmark for future reference for those interested in electronics.

Edit:

As an aside, I too have done a little anodising and electro-plating (in a past life) and used a variable power supply based on a Motorola MC1469R, with both voltage and current control.

Specifications and application notes for that and other suitable devices are readily available on the wonderful w.w.w.

It was so long ago now, that I forget what anodising solution I used, but I do remember getting some advice from a friendly person at a nearby electro-plating shop. They also kindly supplied the solution, either chromic or sulphuric acid (I can't remember which). They also supplied a black dying agent as I required the aluminium to be black anodised.

At some other stage (in the same era), I obtained another solution from them to assist in tin-lead plating of copper PCB (not as good as gold but a lot cheaper and reasonably effective for my purpose at the time).