User BZo - Electrical Engineering Stack Exchange

46 votes

3 answers

11k views

What are these "dogbone" traces for on (1970s era) PCB?

asked Nov 8, 2021 at 0:35

24 votes

4 answers

4k views

Why does this vintage DRAM chip enable circuit require such a beefy resistor?

asked May 6 at 3:47

17 votes

11 answers

2k views

Why was so much TTL logic design "negative true"?

asked Apr 16, 2023 at 21:37

15 votes

3 answers

3k views

Why are these two electrolytic capacitors so hugely different in size?

asked Apr 22, 2020 at 18:17

13 votes

6 answers

4k views

Why does this diode/capacitor combination appear on every board in a vintage computer?

asked May 29, 2023 at 14:51

12 votes

4 answers

2k views

When is it appropriate to mix 74LSxx components with original TTL 74xx?

asked Dec 10, 2023 at 21:25

10 votes

1 answer

2k views

How to safely ground a device plugged into an isolation transformer

asked Mar 11, 2020 at 16:11

6 votes

3 answers

637 views

What's the right replacement for vintage "glass cloth insulation" that transfers heat in Variac?

asked Mar 30, 2021 at 2:35

5 votes

3 answers

1k views

Why am I seeing -5 V or lower on the output pins reading an Intel 1702A EPROM?

asked Aug 17, 2021 at 18:23

4 votes

3 answers

2k views

What tool is used to crimp DIP connectors onto ribbon cable?

asked Sep 2, 2021 at 23:44

4 votes

1 answer

1k views

What is this obsolete (?) video screw connector called?

asked Sep 14, 2021 at 17:59

4 votes

2 answers

898 views

Getting a small AC "reference" from a DC power supply?

asked Jan 9, 2023 at 17:13

4 votes

2 answers

847 views

How to generate +5 V and -9 V voltages to read an Intel 1702A EPROM via Arduino?

asked Aug 12, 2021 at 3:11

4 votes

2 answers

96 views

What is this chip enable circuit doing? (old TTL, with diode, with pull-up?)

asked Apr 4 at 17:52

4 votes

2 answers

382 views

Two X capacitors from lines to ground- why? GFCI fault, even after replacement

asked Feb 14 at 19:26

4 votes

1 answer

145 views

What are these small tubes soldered into through holes for jumper wires called?

asked Jun 22, 2023 at 15:48

3 votes

2 answers

706 views

Why is this zener in series at the base of transistor, and has something failed?

asked Mar 14 at 17:13

3 votes

2 answers

929 views

Old Variac -- chassis ground? is it safe?

asked Mar 28, 2021 at 16:56

3 votes

2 answers

460 views

Is a 2N3906 an appropriate replacement for a BC158(B) in audio amp circuit?

asked May 28, 2020 at 16:53

2 votes

1 answer

85 views

Info/substitution for National Semi's obsolete S-1122 transistor?

asked Mar 17 at 18:09

2 votes

2 answers

152 views

Debugging a problematic old TTL pull-up that's not pulling up

asked Mar 31, 2023 at 3:00

2 votes

1 answer

106 views

How is this bit of logic generating its short output pulse (and is it supposed to be longer)?

asked Feb 3, 2023 at 2:13

2 votes

1 answer

127 views

Disc capacitor ratings for replacement

asked Apr 22, 2023 at 7:35

2 votes

2 answers

82 views

What does a grid-cathode bypass capacitor on CRT do, and why is this one not doing it?

asked Jul 9 at 18:07

1 vote

1 answer

256 views

What's the intuition behind connecting a wire shield to the ground plane on a bare board?

asked Feb 5, 2023 at 22:47

1 vote

3 answers

117 views

Simple TTL: Is there a way to "detect" a high-z state and easily use that to drive other logic?

asked Jan 10 at 20:19

1 vote

3 answers

2k views

Why are one channel's transistors in a power amp getting much hotter than the other's?

asked May 18, 2020 at 22:03

1 vote

3 answers

3k views

When is a non-polarized electrolytic capacitor inappropriate?

asked Apr 21, 2020 at 15:44

0 votes

2 answers

531 views

Transistor substitution guidelines? (and the BC147A)

asked May 4, 2020 at 23:57

0 votes

3 answers

658 views

What are the specific scenarios that an isolation transformer is useful for avoiding?

asked Mar 10, 2020 at 22:59

Stack Exchange Network

37 Questions

What are these "dogbone" traces for on (1970s era) PCB?

Why does this vintage DRAM chip enable circuit require such a beefy resistor?

Why was so much TTL logic design "negative true"?

Why are these two electrolytic capacitors so hugely different in size?

Why does this diode/capacitor combination appear on every board in a vintage computer?

When is it appropriate to mix 74LSxx components with original TTL 74xx?

How to safely ground a device plugged into an isolation transformer

What's the right replacement for vintage "glass cloth insulation" that transfers heat in Variac?

Why am I seeing -5 V or lower on the output pins reading an Intel 1702A EPROM?

What tool is used to crimp DIP connectors onto ribbon cable?

What is this obsolete (?) video screw connector called?

Getting a small AC "reference" from a DC power supply?

How to generate +5 V and -9 V voltages to read an Intel 1702A EPROM via Arduino?

What is this chip enable circuit doing? (old TTL, with diode, with pull-up?)

Two X capacitors from lines to ground- why? GFCI fault, even after replacement

What are these small tubes soldered into through holes for jumper wires called?

Why is this zener in series at the base of transistor, and has something failed?

Old Variac -- chassis ground? is it safe?

Is a 2N3906 an appropriate replacement for a BC158(B) in audio amp circuit?

Info/substitution for National Semi's obsolete S-1122 transistor?

Debugging a problematic old TTL pull-up that's not pulling up

How is this bit of logic generating its short output pulse (and is it supposed to be longer)?

Disc capacitor ratings for replacement

What does a grid-cathode bypass capacitor on CRT do, and why is this one not doing it?

What's the intuition behind connecting a wire shield to the ground plane on a bare board?

Simple TTL: Is there a way to "detect" a high-z state and easily use that to drive other logic?

Why are one channel's transistors in a power amp getting much hotter than the other's?

When is a non-polarized electrolytic capacitor inappropriate?

Transistor substitution guidelines? (and the BC147A)

What are the specific scenarios that an isolation transformer is useful for avoiding?