We need more power Captain!
Often we get a request for a Superpower that can deliver more voltage, more current or more current and voltage than our standard products. Thanks to the patented design, you CAN get more. The SPJ has its TO-220 packaged output device attached to the rear of the PCB. You can remove this device and connect it with "flying leads" so it can be attached to a heat sink, as A. Shan did.
This allows the regulator to dissipate up to the maximum power specified for the output device, which is 60W, without heating the regulator PCB or mounting the entire Superpower on a heat sink as Jonathan Parle did. It does not, however, prevent high current from flowing through the copper PCB traces.
A separate path for load current
(Note! The following is for advanced experimenters.)
Removing the output transistor allows you to wire a Superpower so the load current
never flows through the PCB. Connections for this are shown below:
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With the TO-220 output transistor removed from the PCB and wired in this manner, the PCB
contains the low current regulator control circuitry and the external wiring carries all load current
through the external transistor to the load and back. This allows the circuit to deliver more than the normal 2A,
potentially up to 5 or 6 amps.
The power transistor is shown in the above example as a Fairchild D44H11, which is the normal SPJ78 output device with rated at 80V, 10A, 60W. However, realize that the SPJ78 is rated at maximum Vin=35V because the maximum voltage for its on–board output capacitor (the tan rectangle on the right side) is 35V.
High power and Vout>30V
Vout is set by an internal resistor and limited by the output capacitor as mentioned above. For Vout higher than 30V you can order a custom Superpower and specify your required Vout on the order. We will build your custom Superpower with the requested output voltage and not add the output capacitor.
You can assemble a high power regulator with an external capacitor rated to your custom Vout as shown here:
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Notice the on–board capacitor has been removed and an external capacitor connected from Vout to regulator ground. This should be 100µF or more and have a voltage rating higher than Vout. Also notice the diagram is not to scale—the capacitor will be bigger than the Superpower :-).
Diodes shown in the figure are for protection of the regulator if input voltage falls faster than output voltage, or if Vout gets pulled below ground by some load related condition (e.g. an inductive load). They are typically 1N4007.
A power transistor with higher power rating can be used in place of the standard D44H11. We have tested NJW3218G to be suitable, it is a 250V, 15A, 200W device.
SPJ17 high power circuit
More information coming soon!
SPJ79 high power circuit
More information coming soon!