Power your circuit board when and where you need, by using USB power you already have with you.
Use this space to cheer the creator along, and talk to your fellow backers.
Have a question?
Thanks for the support to our project.
Here is the answer to your questions.
1. Our firmware doesn't have control to the USB connection. How much current got from USB port really depends on the capability of the USB host (Could be USB hub). Some of them can provide higher current (up to 500mA), while other only provide the lower current.
If you need higher current power output, we suggest to use the external AC/DC adapter with USB connector. We have such kind of adapter (UL certified). If you need, we can provide one to you, but it should be easy to find on the market.
2. For the second question, no, we haven't thought about yet, but your suggestion is very interesting and useful. We will take deep look. I might ask you few questions on this.
3. Regarding the 5.0V, since we current use MP1401 as the regulator, it has very low voltage drop (around 0.17V), so, the max output voltage will be close 5.0V, If you need higher output voltage (even more than 5.0), you probably need use the external AC/DC adapter (or 9V battery) to power the unit. For example, we use the same PCB board to build 2 channels battery charge station for one of our clients. It works perfectly. The input of the battery charge station is 12V (using computer power). The charge voltage can be adjusted up to 11V under this situation. So, it can charge single cell and double cell li-ion battery. we build in "stop-charge" feature in the unit as well. If you need more info, you can send email to email@example.com.
Please let me know if you have more questions or comments
Mike and Brad
(...and by 5.5V I really meant 5.0V)
Just to confirm - I see in the current schematic that you have the USB D+/- hooked up to the R8C - does the firmware go through a proper enumeration process to pull 500mA instead of the 100mA default?
Second Q/long-shot request: Have you considered replacing RV1 with a digital pot (e.g. Microchip MCP4018 - http://www.microchip.com/wwwproducts/Devices.aspx…) and using a quad-encoded "mouse wheel" or capacitive swipe zone for manual intervention?
That would open up some options for Really Useful Features like built-in supply ramping and USB-settable/controllable interface.
Great project! I've put myself down for an international 4-pack (aka Canada) so I can have 1.8V, 2.5V, 3.3V and 5.5V going all at once. ;-)
Yes, self-powered variable power supply is a good idea. We have thought about that. Using li-ion battery and one voltage boost chip, we can reach this requirement.
Regarding the high voltage output, yes, we will include this feature in our next version. Actually, we do have one prototype. The output voltage supports up to 25V.
Haha, thanks for your feedback feedback, I love the interactive nature of kickstarter! Well if you're after extra points, what if you made another reward that was a barebones battery box for an AA + booster circuit that could plug into the USB and make it completely self sufficient while mechanically engaging with your box? Double points for using a LiIon battery that recharges off the USB with some kind of low-batt warning! ;)
A really good feature will be current limiting feature and voltage up to 9V, but anyway the hardware is already very good like that.
I used to spend a lot of time in the lab when I was a board design engineer. Now I'm a cryptographic chip design engineer, so I only occasionally go into a lab to try on my designs when the silicon comes back. One of the problems I always encounter is getting hold of useful power supplies. (1) They tend to 'walk away' if left unattended. (2) Modern silicon runs on low voltages (E.G. 0.6 - 1.3v ) and the PSU control ranges tend to very coarse relative to that range.
The idea of having my own USB powered/controlled, voltage and current limit controllable PSU that I can take with me in my laptop back would is very exciting because it would solve all my PSU problems. I don't personally have a need for higher current or voltages, but other people might. I'd pay more for a device with independent current control since it takes an extra knob and display. Being able to control it through USB and script a bringup sequence that ramps the current until the right voltage is reached (or abort if it takes too much) would be awesome since it would be more accurate that turning the knob with my fingers.
Hi James and David!
We have discussed your suggestions and have to agree. As this is the first iteration we clearly have room to improve. At the same time, portability and cost effectiveness are key ingredients. We have started working out how to incorporate current control without adding significant costs to the build. We have also been looking at alternative housings in order to increase the portability. So James, we're going after those extra points you mentioned.
Thanks for the feedback,
Brad and Mike
I agree with the other guy. Think about independent control and display of current and voltage. This is what distinguishes a useful lab bench power supply from a useless lab bench power supply.
Looks great guys! Killer features I'd like:
- As thin as possible (pocketable)?
- If not thin, tiny alligator clips and leads stored within device?
- Press a button to change to Current Control (extra points for independent selection of current and voltage display and current and voltage control)
But if it was just as it is, you have my money! ;)