Hi. Im trying to power-up SSC from the power supply. I bought one that gives 6V and according to specs at that voltage it gives 3.5A.
I am using it to power up Phoenix hexapod that uses 18 HS-645 servos. Everything is working fine when Im sending single leg commands (#0 P1500). But if I send more then 2 servo combo (#0 P1500 #1 P1500 #2 P1500) they move briefly and then go limp.
I was suspecting there was not enough power but by my calculations it should be enough juice for 3 working servos:
each servo uses 350ma*3=1050ma
Any advice be welcome since its second power supply I bought (1st was 500ma only).
Are you attempting to power the VL input of the SSC-32 from the VS supplies rather than the 9V battery using the 9V battery clip supplied with the SSC-32 and the VL=VS jumper removed?
I believe your values are incorrect. The servos will draw over an amp when doing work. It may only be a spike or a surge, but that’s all it takes to reset the SSC-32 if you are powering the logic from the servo battery. Other things that can cause this are; using too small guage wires, twisting wires together instead of soldering, using a cheap low current switch, and even using the wrong settings (current limit) on the power supply. Rest assured it is most definitely a power issue.
I forgot to mention that Im powering up whole board via VS1. I dont use BotBoard but rather control SSC from the computer.
RobotDude, when I look at the specs of HS-645 I see 350MA-450MA for the Running Current. Maybe its idle current that I was looking at but then again, single servo control worked fine even if I used 500ma old power supply.
I switched to the thick wires (same result). Should I solder wires to the VS1 instead of using screws? Did all the checks (voltage settings is correct and measured by multimeter). Im not using switch at all.
I will try to power-up VL from the separate power.
On the side note: before, I used Parallax’s controller (16 servos) but switched to SSC cause it supports more servos. But… even tho Parallax don’t have multi-servo commands in their firmware I was able to move 3 servos at same time (3 asynchronous commands one after another) from my old power supply (500ma).
The specs state that at 6vdc the current is 450mA not 350mA. 18 servos drawing 450mA is about 8 amps, which is consistent with current draw for a moving hexapod. I stand behind the statement that there can be surges that are even more than that when the bot is moving fast.
There is no need to solder the wires. There are literally hundreds of people running hexapod robots with the SSC-32 as is with no modifications…
This will prevent the going limp problem, but there must be a problem with your power supply. I do not believe it will be enough for the hexapod. It really needs 8 amps or the servos will be slower and not as strong.
The problem is due to the processors minimum voltage requirement. It’s not really a problem but just a requirement of the more powerful processor used in the SSC-32.
Jim, can you recommend good power supply for my configuration?
Latest one Im using is relatively expensive ($40). Good news Il return it since 3.5A isn’t enough.
If I connect VL from separate power, will spikes from 18 working servos cripple movements (even if VS1 has 8A)? What are side-effects in that scenario?
Not sure what the failure scenario is for the supply you have. But most regulated supplies will drop the voltage if the current demand is greater than it’s design. Most wall wart style supplies are rated for a given number of watts. So it’s simple ohm and power laws of electronics.
There is also the possibility that your supply is defective.
Can you post a link to it’s specifications just for grins?
Note there is a BIG difference between a battery and a power supply. When you enable all 18 servos at once they demand a great deal of instantaneous current. A good battery can provide this without even breathing hard. But a power supply may not be able to handle it.
If you power the electronics (VL) with a 9vdc battery and power the servos separately no matter what you use, at least the controller will not reset. You may need to power on the servos in a sequence rather than all at once.
I’m not sure where to tell you to go. Jameco has a large selection of power supplies though. Hope this helps.
What batteries would you recommend for me and how long they can run if say hexapod constantly walking?
What is in your opinion safe Amp threshold for the power-supply so it can handle spikes during 18 servos work? I need power supply for only testing - meaning bot will be sitting on the support (legs not even touching ground).
I had a selectable PSU and it did not perform well at all. It gave me all kinds of problems until I bought a dedicated PSU from Lynxmotion like this one:
6V 2amps
Provides plenty of power to run my ABB, SSC-32 and two LEDs on my Brat equipped with 13 servos.
The more current the better when choosing a power supply. I don’t know what the problem is with the velleman one though. It might be interesting to measure the voltage at the SSC-32 terminals when it’s running to see what happens to the voltage when current is drawn. Do the connectors look robust where you plug in the style plug you want. Can you show us what your wiring looks like with a jpg image? Sometimes a picture is worth…
If you were to use a battery it will provide the required current as long as the capacity of the battery will allow. If the robot draws 1 amp and the battery is capable of delivering 1 amp/hour, it will operate it for one hour. It’s all just math really. Our large NiMH batteries are good for 2800mAh, or 2.8 amps in 1 hour. Drawing 8 amps from it will operate the bot for 21 minutes…
