Koolance PMP-400 pump (DDC+PLUS) with BONUS
 

FYI --

http://www.koolance.com/images/pmp-400_p0.jpg

The PMP-400 is a standalone DIY version of the pump used in Koolance PC4-1000, RP-1000, and TNK-400 products. 3/8" (10mm) ID, 18W, 9-13.2VDC, >6 L/min (1.8 GPM), >3m (10ft) head, with tach lead.

http://www.koolance.com/shop/product...roducts_id=334

The BONUS part is the pump speed control for any DDC pump.

http://www.koolance.com/images/pcb-pwm10p_p0.jpg

The PCB-PWM10P control board allows manual speed adjustment of the Koolance TNK-400 pump and reservoir.

http://www.koolance.com/shop/product...roducts_id=324

Re: Koolance PMP-400 pump (DDC+PLUS) with BONUS
 

How does that speed control work? Does it supply continuous voltage to the motor controller circuit and vary the current and timing for the coils? That'd be much more flexible and quiet than chopping the voltage supplied for the whole DDC (PWM) or lowering voltage until you get brownout conditions for the onboard motor controller.

Re: Koolance PMP-400 pump (DDC+PLUS) with BONUS
 

Well, looking at that circuit, it seems like two I made a few years back to control sets of fans. So I'll venture a guess.
The PWM wave feeds the base of the power transistor, regulating the output voltage to the pump. Mine were 3A max rated. So that one should be at the very least 1,5 A. 3 is on the spot. Something like a TIP32 or similar.
Point is, the PWM isn't used directly on the pump.
Pump is fed through the power transistor. If it's a "slow" response transistor, then the pump feed is pretty much linear.

Re: Koolance PMP-400 pump (DDC+PLUS) with BONUS
 

Well, there are three wires going to the DDC, and I vaguely recall the DDC having a ground, +Vpump, and +Vcontrol.

My original theory was that the +Vpump line was invariant and higher current while the +Vcontrol would feed into the pump's control circuitry. The pump microcontroller would run off of the steady voltage from +Vpump, while using the +Vcontrol as input. Then, as +Vcontrol went up/down, the pump would regulate the amount/length of current sent to the motor windings.

However, that's probably wrong. It looks like the invariant current is being sent to the pump's motor controller, while the outboard controller board simply uses DC-DC (via PWM) to vary the voltage being fed to the coils. Now that I think of it, that probably makes more sense, since you probably don't need to change anything with the timing of the pulses sent to the coils. You just need to vary the amount of current. The outboard controller does that and you don't have to have a complicated circuit on the pump.

Re: Koolance PMP-400 pump (DDC+PLUS) with BONUS
 

Brian, the old DDC has +V, ground and RPM. It's the same as a standard case fan. The 18W version may have changed, but my instinct says not.

Re: Koolance PMP-400 pump (DDC+PLUS) with BONUS
 

Bummer! I guess I'd rather have the tach than the better speed control, but it's still a let down. Well, it may be fine. The range of "usable" RPMs may be covered by all voltages supported by the DDC control circuitry.