HeavenLights DC 5v to DC 9v Converter Step Up Voltage Converter DC - DC from 5V to 9V USB to 5.5 x 2.1mm

Since I really don't like the battery pack which our health insurance company sent to us with the breast pump, after I did some research, I think this converter should be an easy solution. You can use most of the power banks which have 5V 2A output as your power source. And it works great so far.

The device itself works well within its specifications so far. However I can only give it two stars as the cables broke at the USB connector and at the power cable out of the device after only a few uses with careful handling. This seems to be due to missing/poor stretch relieve and brittle cable material on the copy I received. While I have tried a repair with electrical tape it does not seem very stable and it is likely only a matter of time before it it completely broken - copper was already visible on one of the conductors.I bought this to power Nikon DSLRs from a battery bank. A note is that the 1A output rating of the device derived from the 2A specification of typical USB power devices is not adequate to supply peak current that can be as high as 2A drawn by the camera during mirror movements, while average current draw is much lower and well withing the 1A specification. Intermittent lockups of the camera's mirror mechanism occurs without remedies. This is not the fault of this device as it is due to the typical 2A USB output specifications, thus no stars subtracted because of this. I solved this problem by connecting a 9V 1F super capacitor across the power leads to the camera that will limit peak current drawn from the device to ca. 1A. The capacitor is charged though a current limiting resistor and discharged though a schottky diode, another diode supplies power directly to the camera in parallel from the device.

I can use my Korg Minilogue XD ANYWHERE!! With this (and a ‘yellow tip’ adapter) I can play my synthesizer anywhere - busking, camping, anything. I love it! ( but keep in mind that the 5.5mm tip may need to be sized differently for your application)

If you want to power 9-volt guitar/bass pedals, use something like this https://www.amazon.com/gp/product/B075R64SCQ/ref=oh_aui_detailpage_o02_s01?ie=UTF8&psc=1. Pedals are typically center negative, and their current needs usually stated in milliamps. So this will provide up to 1000 milliamps with the required 2-amp input. The converter was able to power a few pedals I'm interested in by using a reverse polarity cable. Haven't tried powering a chain of pedals yet, may follow up this review with an update.

I bought it to keep my DSLR camera which needs 9v to be charged. It works perfectly . now i use my camera outside with 5v power bank and this converter and i don't have to worry about battery anymore .Very happy with this solution . Recommended!

Standard 5 to 9v converter. Bought it 2 days ago because my old converter burnt out. Just tried it today and it works great. Pretty much as described. Seller is friendly and has good return policy if item is DOA. 5/5

Faulty device. Tried with 2 different units with no luck. Also, they do not offer returns on this product.

The product worked great and the delivery was very fast. I've found a dozen uses for it and will definitely buy another one. Good service and good product.