SOB1400

Wayne,

From your previous comments, I understand that the SOB has about a 50-50 chance of working when choosing sense resistors that give between 1200mA-1500mA output. Is this correct? I would like to order an SOB1400, but I'd like to know how you will handle returns/replacements if the SOB1400 doesn't function. I assume that function would be binary -- it either works and puts out full power or it doesn't light up the LED (I'm looking to drive a 2S2P MC-E with 3x18650)? Thank you.

I typically will work with any customer on any return/exchange within reason. I don't have any solid rule on exchange. My general rule is the customer should test the board before installation in the product. Typical I will deny exchange if the customer had doubts in the pre-test, but, continued to install it into the product or never pre-tested the board in the first place (basic common sense). That usually voids any warranty exchange. Who knows if damage was done during installation, proper wiring, load, polarity ect. Since the boards come untested I highly recommend customers to buy one spare in case one is defective. I really never state anywhere that I gurantee the board works in the first place and every exchange is a financial loss on our end. The small profit on the board is negated by the replacement unit, time spent in email/PM communications and return postage.

For the current SOB the current consensus is maximum is around 1200mA even though the design has potential for up to 1.5A.

I believe I know how to make it reliable up to 1.5A, but, this has not been a high priority and it has not been done yet. Until I can see if I can correct this situation I can only recommend 1.2A as the maximum and it would be the customers risk to push beyond this at the current moment.

If this is for a run of lights I'd be more inclined to try to push this up in the queue and do more bench testing to see if I can stability to 1.5A.

Nothing I said above is cast in stone. I'm only speaking off the top of my head which btw is mostly full of air.

I'm currently working on the new auto-cal software for the GDuP and a new version of the GDuP board, new software UI for the Remora and fixes or changes to the Remora to get 0-100% PWM control with the Remora and many other projects I can't mention at the moment.

You are correct. You have a 50/50 chance the SOB will work at 1.4A. Either it works or doesn't work.

Wayne

Thanks. I see that I can combine sense resistors to get an SOB1185, SOB1227, or SOB1278.

In terms of the 1200mA-1500mA range, do you know if it is a sudden change in reliability when crossing the 1200mA lower limit, i.e., good to go with an SOB1185, but 50-50 chance with the SOB1227 or SOB1278?

Justin;

You've exceeded your message store, so I can't PM you. Can you please delete some?

Thanks,

-John

Justin Case said:

Thanks. I see that I can combine sense resistors to get an SOB1185, SOB1227, or SOB1278.

In terms of the 1200mA-1500mA range, do you know if it is a sudden change in reliability when crossing the 1200mA lower limit, i.e., good to go with an SOB1185, but 50-50 chance with the SOB1227 or SOB1278?

Click to expand...

I do not know much about the specifics. I'm only going by what customers have said on the forum and via communications to me. I don't know if it will maintain regulation over temperature or what the true effect is. Somewhat that has more experience is MilkySpit. You can try contacting him and see if he can shed additional information on the subject.

Wayne

Justin, you can stack two .12s & a .18 to give you 1194. Stacking the sense resistors to use three in the combo opens up a wider range of choices. Back then this was the only option before Wayne made the .05 resistor available

I've built a number of McLux heads using the old DB at 1194, 1250, 1500 & never had a failure. But again these were DownBoys & not SOBs. I can't comment on the reliability but I've never had one come back to me & I built these years ago long before SOB was released.

I've used a number of SOB1500s in builds & two DB1500s in parallel & I never came across one that did not work or has had failures. Not sure if it made a difference but those were all potted. I'm not saying it perfectly safe, just saying that I haven't had any failures yet.

Just want to clarify. The board will if it does run at 1500 can be run free standing. The thermal I was referring to relates to the unstability or lack of full regulation. If the board runs there are no thermal issues with the core design. I believe noise is coupling into the feedback node which is worse at higher drive levels and this noise causes reduced output current. It thinks it is regulating 1400 or 1500, but, the output due to noise is less than expected. Whether the noise coupling gets worse over temperature or not is something I have no idea at the moment. If I am correct and this is what is going on, then scaling back the sense resistors to put them at a lower impedance should solve the noise suseptibility.

The core converter is the same one in Daves SP005 and in that design it is stable at 1.5A and higher.

Wayne