Noticing no output voltage on H Bridge IC (with shift register) - Page 1
Forum section: electronics / beginners

author: Cranberry
author_rank: Contributor
timestamp: January 13, 2016, 06:57:54 am
content: Really, the subject should be: Noticing no output voltage on one of the H Bridge ICs and low current on other H Bridge ICs output regardless of Vcc2 supply increase/decrease voltage (with shift register).ICs being used:3 SN74HC595 shift registershttp://www.ti.com/lit/ds/symlink/sn74hc595.pdf4 (ideally want to hook up 8 ICs for a total of 16 electromagnets) SN754410http://www.ti.com/lit/ds/symlink/sn754410.pdfLoose circuit fritzing diagram (attached)– assume h bridges 2-4 are hooked up similarly to h bridge 1 (fritzing was getting too messy).Context: working on something like this:www.e-alexander.net/magic_slippers.phpI'm using a DC adjustable power supply and have set the power supply to 5V for Vcc2 (supply voltage) in one instance, 8V in another to see if the current changes and have noticed that the output current remains pretty low throughout.I'm using 3 shift register ICs to hook up 4 H Bridge driver ICs for a total of 8 electromagnets + earth magnets hooked up to the Arduino.My hand-wound electromagnets have a resistance of approximately 9 Ohms each. I have arduino code based off ofhttp://bildr.org/2011/02/74hc595/that switches the polarity of the electromagnets and turn them off.With a 5V or 8V power supply, values stay pretty much the same, what's the reason why?:1st H Bridge ICVout1 = 0.7V, Vout2 = 1.27V, Iout1 = 0.08A, Iout2 = 0.08AVout3 = 0.7V, Vout4 = 1.31V, Iout3 = 0.07A, Iout4 - 0.07A2nd H Bridge ICVout1 = 0.79V, Vout2 = 2.26V, Iout1 = 0.16A, Iout2 = 0.17AVout3 = 0.81V, Vout4 = 2.24V, Iout3 = 0.2A, Iout4 - 0.2A3rd H Bridge ICVout1 = 0.71V, Vout2 = 1.21V, Iout1 = 0.08A, Iout2 = 0.05AVout3 = 0.7V, Vout4 = 1.03V, Iout3 = 0.04A, Iout4 - 0.03AI notice that my 4th H Bridge IC does not input a voltage at the output nodes, but theEnable 1-2 reads 4.58V, In1(datasheet 1A) = 0.19V, In2(datasheet 2A) = 4.5V, Out1(datasheet 1Y) = 0V Out2(datasheet 2Y) = 0.02V.Enable 3-4 = 4.8V, In3 = 1.22V, In4 = 1.63V, Out3 = 0.13V, Out4 = 0.12V (somehow no current).What could be wrong?

author: Cranberry
author_rank: Contributor
timestamp: January 14, 2016, 08:39:04 pm
content: I'm replying to my own post because I had noticed the culprit was bad chips(?) regarding having no output voltage.I left the chips on the breadboard unconnected to anything. Could someone explain to me whether that secretly does something that would cause adverse effects to the chips? Could something else have occurred that would result in that?

author: jancumps
author_rank: Unknown
timestamp: January 14, 2016, 08:53:25 pm
content: Both ICs have this remark in section 13 of their datasheet:Quote

author: Cranberry
author_rank: Contributor
timestamp: January 14, 2016, 11:22:37 pm
content: Okay. That answers part of the question (well a complete question). I'm still learning how to understand these datasheets.Edit: Does that mean to put the pins to Vcc?Another question still resides: Does the shift register regulate the max amount of voltage/current going through the bridge (as diagrammed)?I notice no matter how high my Vcc2 (power supply voltage is) it seems like my output voltages and output currents remain the same.Think I figured it out.